I got banned from Demonoid back when I was just starting to use bittorrent for the first time and didn't understand it.  I was leaving my downloads in my download folder so that they would seed, but I wasn't force-starting them, so they weren't automatically seeding.  They were just sitting there in a queue waiting to be seeded someday.  So my ratio got out of whack and one day I went there and got a nasty message about leeching and I was banned.  I contacted the site owner or an admin, apologizing and explaining why I had been inadvertently leeching.  The guy acted like a five-year-old about it.  Seriously, it was like he looked over and saw me playing with one of his discarded toys on the playground and had a temper tantrum, while I just looked around uncomfortably and said, "I'm sorry . . . I didn't know it was his.  It was just sitting here."  In the end he reluctantly gave me upload privileges back so I could fix my ratio.  I started some files seeding, but I never actually went back to download anything.  He was just such a dork.  
Sorry if it's any of you.