Well, if you're writing about a certain profession, a specific area of the country, a certain city, then we need make sure we're accurate enough to be believable. And for those historical authors well....that's an entirely different story. I came across a great article on why it's imperative for an author to do their research and use it properly in their stories. Such inaccuracies and discrepancies could make or break an author's career.
this is from Anne Marble at writing-world.com:
Research Flaws in Romance Novels
by Anne M. Marble
There are two big mistakes a romance writer can make when incorporating research into her novels. One is neglecting the research and making huge factual errors. The other less obvious mistake is overusing your research.
"Corn on the Cob and Gaslight, Oh My!"
Mistakes in historical romance novels can be very obvious. One best-selling author not known for her historical accuracy had her Regency era hero complaining about the "simpering females at White's." However, White's was a men's club, so there were no females, simpering or otherwise, to be found. This novel was full of errors like this, and the characters acted as if they were modern-day people in fancy costume. Readers who went to this book looking to be immersed in the historical environment were disappointed.
Look out for anachronisms. These can pull a reader right out of your story. Are your Medieval warriors dining on corn on the cob even though corn wasn't brought to England for hundreds of years? Does your heroine read by gaslight in 1800, even though that wasn't introduced to London until 1817? Even worse, do your Victorian characters have modern names, such as (shudder) Crystal? Then maybe you're not at home writing in that era.
If you're writing novels set in the American West, you have a new set of challenges to face. Many romance writers have their characters travel by train. Unfortunately, they forget to look up information about trains of that era, so they have their character traveling on tracks that don't exist. Other writers err in the other direction, having their characters travel by wagon train when they could've easily taken a train for less cost. When you write romances set in the West, many of your readers live in that area, and they will spot those mistakes quicker than you can say, "Howdy pardner!"
Mistakes don't have to be so obvious. Inaccuracies can be subtle yet damaging. One of the biggest flaws in many historical romances is that the characters don't behave like typical people from their era. For example, if your frontierspeople all treat Native Americans fairly, or if your British lords are kind to the Irish servants, then you are neglecting the historical context of your story. In addition, you may be sacrificing potential drama.
When you write a historical novel, remember that you're writing about another era. The culture is often as alien as what you'll find in a science fiction novel. In all too many historical romances set during the Regency era, the courting couple often go off together, alone. But this was simply not done at this time. A couple going off unchaperoned would create a huge scandal. Proper women simply wouldn't allow such liberties.
This isn't to say that your characters cant be iconoclasts, but you must explain why your heroine is strong-willed enough to refuse to marry the husband her father picked out for her. After all, most women of the upper classes accepted that their marriages would be arranged. So unless you have portrayed her as rebellious, don't have the heroine act with shock and horror when she learns her father expects her to marry a man she has never met.
Do you plan to write only contemporary novels? You will still have to do research. Is your book set in a certain city? Is it about a particular profession or region? Make sure you get all the facts right. If you make obvious errors, such as having your characters visit the Baltimore Aquarium when the proper name is the National Aquarium in Baltimore, you risk alienating readers who know the area. The same is true if you have a character referring to "Silver Springs, Maryland" when the correct name is "Silver Spring." If you make lots of subtle errors, such as having your characters get take-out from exclusive restaurants such as Sardi's, readers will think you don't care about your setting.
Don't base your research on what you've read in other romance novels. Remember -- those novels might have gotten the facts wrong. Also, remember that research is more than just facts. Research is a great way to find information that can help you out of a tight plotting situation or give your characters a more detailed background.
"Here, Duke! Here, Duke!"
Authors often get the titles of the British nobility wrong. It's a very basic error, and it's bound to annoy your readership.
If you want to write British historicals, it's imperative to learn the proper way of referring to nobility. Mistakes can make you look like a newbie. For example, let's say your hero is the Duke of Earl. Do not have your heroine call him "Duke." Only the duke's familiars are allowed to do this. Everyone else must call him "Your Grace."
This is a complicated topic and too involved for a couple of paragraphs. Luckily, there are lots of web sites to help you research titles. Romance writer Jo Beverley has a wonderful page about the proper use of titles at http://www.jobev.com/title.html.
"As You Know, Jane, Some Writers Like to Show Off."
Research can pose another problem to the romance author. There is the danger of being so in love with the facts you've discovered that you want to tell the world about them. All of them. That leads to a potential deadly flaw -- not interspersing information carefully into your novel.
Recently, I read a novel where the action stopped for about two pages because the author decided to lecture the reader (in an omniscient voice) on the importance of the rain forest. This came in the middle of a novel set during the 1800s, before anyone knew that the rain forest was important to the environment. So it was not only a huge expository lump, it was also an authorial intrusion.
The rain forest seems to have an odd effect on writers. I read a contemporary novel dealing with issues of the rain forest. Potentially interesting background became dull and listless because characters who felt strongly about the rain forest would stop and tell each other how important the rain forest was. I kept expecting one of the characters to suddenly say, "Stop! I'm a research biologist. Don't you think I know all this stuff?" But the characters didn't do this because they were being used as "sounding boards" for the author.
There's nothing wrong with incorporating research into your novel. But you have to break it down into smaller pieces, and you can't have characters lecturing each other on things they already know. (See, science fiction novels aren't the only ones that suffer from infodumps.)
Don't include details for the sake of showing off. Try to include details because they add to the story. Do they advance the plot? Reveal character? If you're a good enough writer, you might be able to get away with more detail, but you'll have to watch yourself. Some writers lavish their attention on trivial details and end up writing dull stories. Others seem to know every trivial detail but forget to fit them in the context of the times.
Don't forget that you're writing to entertain. Some poetic license may be necessary. It's possible to be too accurate. Few readers will want to read about a Medieval hero who never takes a bath or a cowboy with bad teeth. They will also have a hard time accepting a dandified hero who wears pink and waves a perfumed scarf in the air. On top of that, readers have little patience for writers who use realistic historical dialogue because that can be impenetrable to modern readers. (And whatever you do, don't add lots of "perchances" and "tis's" to make the dialogue seem historical. Most likely, you'll end up with a "faux" historical atmosphere.)
It's All in the Details
The amount of detail in your novel will vary depending on several factors. Some publishers prefer novels that use historical background as "wallpaper," while others prefer novels with excruciatingly researched details. If you're more comfortable writing a novel where the history serves as wallpaper, then go for it. This style of historical background is much better suited to romps and farces. However, you can raise your novel above the crowd by making sure that while you don't let the historical details get in the way of your story, those details are still accurate.
Also, keep in mind that some types of books require more research than others. Regency fans are sticklers for historical accuracy, while readers of historical novels set during the Regency are generally less demanding.
Finally, remember that research isn't everything. You must have interesting, sympathetic (or at least charming) characters in a fascinating plot. That comes first. However, good research can make a potentially generic book ("Oh, not another guardian/ward novel.") into a keeper. ("Gee, I didn't know that men during the Regency wore shoes made of...")
A final word. Some readers won't care. They want to be entertained, and they don't let inaccuracies bother them. If you don't mind writing for this audience, then go ahead and have fun. You might even become a best-selling author. However, you won't reach those picker readers, and they are the more rewarding audience.