One thing I hate, kids.

I hate them. They are immature. One noticable thing: If you cant tell whether a person is a kid, check how many times they cuss. If you see too many 'fucks' or 'shits', its quite obvious. They want to feel grown up. Do you see an adult posting every cuss word in the dictionary about how he or she cant make a movie? I dont care!

Another thing, People who post a negative response to a negative comment and vice versa. For example:
"You really need to work on this. Its really bad"
Response: "go hang urself. lest i have more balls than you"
Ex 2:
"This movie was well made! Good Job!"
Response: "Glad you liked it! It took me days!"

With negative comments, I always consider it critisizism. I appreciate it. I dont care whether or not you liked it. I enjoy reading every comment I get.