Oh god. I can go on about this for hours, but i wont
What I mainly hate is not being appreciated enough for the work you provide.
I remember seeing this person's background and noticing that they needed a more welcoming design (the last person just put pictures together using gimp).
I created one for them out of my spare time and they said they liked it and they happily used it.
HOWEVER, they wanted constant updates and nothing was ever perfect.
I spent hours on different designs and all i got was "meh, i dont really like it. Try something else. More shiney"
WHAT? MORE SHINEY?. I could splatter glitter all over it and it still wouldn't be shiney enough for you!
Another would be creating drawings for others to use as thumbnails or avatars.
I would get people inboxing me to create a thumbnail for them in exchange for nothing.
literally messages like:
"Hey, I need a minecraft thumbnail. Draw one for me. Bye thanks."
WUT.
People don't understand how much time i would put into a drawing for them and they couldn't decide what they actually wanted.
So, i permanently stop doing requests and only comply when its my CLOSE friends.. .*sigh*