The customers who want a certain color but then choose one that looks totally different when applied and I sit that that's the right one even when I tell them that I have seen how that color looks when applied and it's not the one they have in mind. Naturally they bitch until I do it and then bitch again when they find out I was right and promptly ask me what I did wrong. Like lol I freaking told you but you had to have your way.
