If your post was somehow bad, you more or less generally get a pm from a mod.
You can talk it over. Spamming just gets temp ban. Fraud is perma ban and ip is recorded.
The policies are pretty fair.
Those who got banned are known for being a bit ragey. I like a lot of the people that were banned but I could definately see how they were.
Not too sure what it is in the context of a Head Fi forum.