Oh! I should mention the middle man scam. I was a victim of said scam. I knew it was a scam, had my roommate sitting next to me play as the middle man that the trader requested. After blatantly telling my roommate it was a scam, I asked for my skins back.
Well, he decided it would be cool to send the trade offer to the SCAMMER, and not ME. My roommate SENT the offer to the scammer. The scammer didn't even have to do anything. Mind you, this was before the whole mobile authentication/email confirmation business came about. I lost a factory new Glock Fade, three Falchion knives that I unboxed that evening and an AWP. But at the end of the day my roommate paid me cash for the skins I lost so I ended up making a profit off the knives I unboxed.