You know what really bugs me?
People who hire you as a consultant because of your specialty in historical costume, then refuse to believe you when you tell them that poor people from centuries ago did NOT change their clothes every day. Or even every week. Or wash them overly often, for that matter. Because, y’know, sometimes they only HAD two outfits. And because a lot of times washing meant taking things apart and then having to sew them together afterward, which got rather time-consuming when you were busy trying to not die of poverty.