Thanks to pop culture people assume everyone but the royals smelled like crap in the Middle Ages, knights were heroic figures who kept the kingdom safe for common folk, and scientific progress went boink thanks to the church.
But historical evidence shows these notions are pure myth, and the Middle Ages were both cleaner and dirtier than we've been told.
Heard the one about the stinky serfs?
Working in the fields all day does make you grimy, but people in the Middle Ages continued the Roman tradition of taking communal baths, and there were even baths made just for workers and craftsmen.
They washed up before and after eating, offered to bathe with guests to be polite, and went through nearly as much soap as we do today:
Medieval demand for soap (usually made from animal fats, with a variety of oils and salts added) was so great that by the 13th century, soap was being made on an almost industrial scale in Britain, Italy, Spain, and France.
Folks kept clean until the Black Plague made them afraid to bathe, believing that bathing opened the pores and thereby made it easier to become infected by the Plague.
Now if you want to see dirty you need look no further than the knights, who were less chivalrous heroes and more ruthless gangs of greedy mercenaries who cured their between war boredom with bloodshed:
Toward the 11th century, many of the local lords started bickering over who would get a slice of the Holy Roman pie that Charlemagne baked, and the knights were at the forefront of these petty wars. These "wars" were less Braveheart-style epic battles and more knights rolling up into villages and slaughtering everybody.
The chivalric code was introduced in the 13th century in order to keep these angry young warriors in line, but the code said nothing about defending peasants so the slaughter continued.
And lastly we discuss science in the Middle Ages- since the Evangelicals and other religious groups are anti-science these days we assume Medieval monks were anti-science too.
But the Catholic church actually saved science, and much of the scientific knowledge recorded by the Romans, from being destroyed by invading barbarians:
The church went about setting up monasteries across Europe, and along with the monks came the monks' massive libraries. Monks were just about the only educated people in the early Middle Ages, and pretty much everything we know about this entire time period was written by them.
As time went on, the church stepped it up a notch and started establishing universities to foster the preservation of knowledge. You may have heard of a few of them: Oxford, Cambridge, and the University of Paris (not to mention pretty much every other top school in Europe).
Medicine also made massive advances thanks to the university system. Contrary to popular belief, dissection of corpses was actually fine and dandy with the church, and medieval universities often did it in the basement (OK, so maybe it wasn't totally fine and dandy). By the 14th century, there were functional hospitals, and doctors had learned how to use antiseptic when lopping off people's body parts.
Read 6 Ridiculous Myths About The Middle Ages Everyone Believes here (NSFW language)