Correction: You get banned for verbal abuse, negative attitude, or being incredibly offensive after being warned multiple times to stop. Trash talk is fine if it is in good jest and isn't offensive or unsportsmanlike.
The only people who get banned are people who don't know where to draw the line. Anyone who thinks normal people who do normal things get banned are incredibly wrong and are probably attempting to troll or be disingenuous about the reasoning behind bans because they ARE one of the toxic players.
If you read this signature, then that meant that I had control of what you read for 5 SECONDS!! http://imgur.com/n8yh1