Bad feedback does not get you banned, it is if you break the rules. You get infractions for breaking the rules and if you get ten, you get banned. Some offenses get you banned quicker than others like spamming the forum. Read the rules above for some clarification.
I am sorry. I think I was a bit harsh. Read rules/faqs and search around and you will find the answer of questions like this. No Offense...
they broke or didn't follow the rules they will get infractions. got enough infraction (10) you got banned. when each infraction expired (less than 10 points) they will came back to life but with Banned tag with them for a while. good suggestion is read the rules and dont break it.
Weirdo... Some repped me with note "Harsh!" I don't know its was green or red but I am sure it was red. Just curious who was that?
Everything from duplicate accounts to getting too many infractions. If you want to see the easiest way one gets banned, do a search for "AnthonyCEA".
Some attack other members... There are plenty of reasons, you can see them all in the thread Slacker mentioned.