1. Disrespecting GM's. This is not allowed, though sometimes a GM will willingly tolerate it, sometimes you just simply get banned for it. Please don't try to justify your argument, disrespecting a GM is disrespecting a GM. If you aren't pleased with the way they act contact an Admin about it.
2. Hacking. This is clearly not allowed, in any way.
3. Scamming. Many people get scammed, but you better hope if you do the person you're scamming isn't getting proof of it. Or you'll be banned.
4. Fighting. Depending over what, and how far the fight went, you could easily be banned for it. Try not to get into too many serious bznz fights. (:
There are many other reasons as to why you could have been banned, but these are the main reasons.