Something that regularly irks me in fantasy novels that are set in medieval settings is the fact that they whitewash the world. This happens a lot in romance novels set in this period too. Enough so that it had become a running joke between my best friend and I, with her reminding me that castles were warm and cozy and I reminded her that heroes always had to be muscular males (which always made her laugh because she was in a gay relationship when this conversation came up and we were trying to determine what the ideal hero was supposed to be). The whitewashing of the dirtiness and generally disgusting parts of the past and settings that are based in it is a type of romanticism that I think the genre could do without.
One thing that I actually like about the A Song of Ice and Fire series (Game of Thrones is the first book and the title of the television show based off it.) is the fact that Geo. R.R. Martin does portray the ugliness of the world. He doesn't try to pain his setting as one that is free of the attendant difficulties of that period. In keeping the more unpleasant aspects of that era in the picture, he adds a greater level of realism to his work. Yes, we can tell someone that a peasant lives in a hovel with their animals. Unfortunately, the image that comes to mind is a clean dwelling with clean animals that basically stand around and look pretty. When the truth is the dwelling is going to be dirty from what the animals track in and if they void their bowels or bladder indoors (which had to happen from time to time just on the basis of probability and statistics). The truth is that the dwelling was poorly lit and poorly heated. The truth is that there were rodents in the rushes that thatched that hovel and rodents scurrying around in the living area of it as well. A peasant's hovel was not the clean pretty thing you see in children's books.
And castles had their share of problems. The list is a bit too long to slap up here but a cursory bit of research into how people lived in castles will show you that they were also dirty places and were terribly heated. It would tell you that they were dark because they were poorly lit and lacked natural light. It would tell you many, many things that would put all but the hardiest of medievalists off from the idea of wanting to stay in one for a night, let alone live in one. (For the record, I am one of those hardcore medievalists.) They were nothing like what Peter Jackson portrayed in the Lord of the Rings movies. The people were not half so clean and well fed. The list of ways that the fantasy stories get the history wrong is too long to present here and that's really not my goal.
I want to make a case for presenting all that ugly stuff. Every story requires a conflict. Too often, it is assumed that the conflict must come in the actions of characters opposing each other. When we look at history, we see that there is lots of conflict in the story of these people's lives. It came from their environment. It came from if they had the bare necessities for survival. It came from the dangers that were present at all times, be it those of rancid food (because food preservation was nowhere near as advanced as what we had in the 1800s, let alone today) or illness. I'm not talking about something as dramatic as the Black Death. Influenza killed people in those days. A bout of bronchitis could (and most likely did) prove lethal all on its own. Then incorporate the medical technology of the era and illness becomes even more horrifying. A simple case of the common cold could possibly kill you if you weren't lucky.
Some would say that conflict coming from things like the dangers of using an open pit latrine or food poisoning are not as interesting as the conflict that comes from two characters fighting. I would argue that in the hands of a skilled author, even a case of the common cold in modern times can become a conflict that would interest the audience and advance the plot of the story. I would furthermore argue that not taking these factors into consideration is doing yourself and your readers a disservice. It is messy and depressing to read the history of the eras we base our material in. The trade off of this work, however, is creating a world that draws your readers into the story.
That, my friends, is one of the goals of writing a book. We don't just want our audience to passively look at the words on the page and come away with a dry sense of what the story was about. We want to draw them into the story and present human elements that they can connect with. We want to have our readers come away from our stories having gained something. A good book may tell a technical marvel of storycraft. It may be an exemplary example of sentence construction and how to organize material on the page. All of that technical skill, however, falls flat if your reader is not engaged in the story. Take the time to write out the dirty details of the world your characters move in. It makes the experience more believable and real to the reader. And that will increase your chance of moving the reader to emotion and the imaginative envisioning of your story. The more senses you engage your readers in, the more they will remember your book.