Omg, I know exactly what you mean. I have an artshop on gaiaonline and this chick requested soo many photo edits. They take me a little over an hour each and she will send me like five at a time and the VERY NEXT DAY send me messages hassling me about why they aren't finished and she has never ONCE thanked me. Now, I only charge 10k a photo edit, which is equivalent to like 25 cents RL money, so it's ridiculously low for over an hour of my time. Finally, I just decided that it wasn't worth dealing with people like her and stopped doing it altogether.
And she would be soo picky! I would do a photo edit, then she would change her mind and say things like, oh can you add in this picture of a snowman?! or add more swirls! or more makeup! multiple changes on a single image. I just gave up. It wasn't worth it.
I can't count how many messages I got that asked, "when will u be done" or "where are my pics!!!" or "ADD MAKEUP!"
/rant