This isn't really a scammer thread, but more a "seller beware" thread.
Mr. "Highs on Bass" and I made a transaction which involved the following: me selling him 20 tweeters (10 pairs) for 15$ shipped. Everything went smoothly until he got the speakers. He had already pm'd me about all the details before the transaction, and I'd answered all the questions he asked. (including flush mounting and price, etc).
First off, he was upset that he couldn't flush mount them in his vehicle (which we'd already talked about in pm's). Also, he was mad because he found them at a better price after he'd already bought them from me.
Instead of pming me about the problems, he posted in my thread about how I was a bad seller, and gave me negative iTrader feedback, all before making any attempt to contact me.
Eventually, I refunded him his money, in full (including shipping costs, which I ate), and pm'd him after said refund, asking him to take more time to keep in contact with me, instead of make me look like a bad seller. He still has the tweets, too. So he got 20 free tweeters, and tried to make me look like a bad seller in the process. All in all, make sure you protect yourself when dealing with this guy. VERY shady