One of my biggest pet peeves is when someone doesn't know the difference between copying and referencing. I won't show examples because I don't want to pick on anyone, but I see this happening with a lot of people, even those big-name artists on DA.
A reference is NOT looking at one picture and copying the pose, facial expression, and maybe even the clothing. Referencing is when someone, say, wants to draw a wolf (or something, just an example) character but has no clue how, so they look up many pictures of wolves and study the anatomy/patterns/poses or whathaveyou, and draw from that knowledge. That is a reference.
Copying is drawing the red dress in
this picture on your character. Calling it a reference makes me rage. You didn't reference the dress, you outright copied it. (not to mention, zambi would kill you xD)
People get so torn up if you call them out on it too. Like 'NO WAI THIS IS A REFERENCE SEE THE HAIR IS DIFFERENT.' Please don't do this. Not all copying is bad either. That's how lots of people learn. But if you're going to copy and put it up for the public to see, at least have a the balls to admit you copied. I'm not a fan of displaying copied work, but I won't crucify you for it until you tell me it's a 'reference.' ;)