Tits who get smart and jack the price up if you show a hint of enthusiasm.
Mate does a trade on an Amp, bloke trades B&W 805 diamonds. Mate is happy until it is pointed out by another mate that them tweeters are not diamond tweeters, but tweeters from the 805S. Sh#t, them diamond tweeters are nutritiously fragile, they just shatter, plus they are hellish pricey. Never mind that the speakers actually sound better with the 805S tweeters. The fact is they are no longer diamonds and are now worth a third of what he traded them for. Eventually my mate hounds the creep down and after some threatening and some shaming manages to get some money still leaving him having to suck up quite a bit.
Fortunately I have been very fortunate so far in my purchases. I did sell a brand new satellite decoder to some tit - unopened sealed box. He returns it the next day, box ripped open, yea ripped open and everything else ripped out the plastic bags and just chucked in the broken box. I do not want it anymore, I want my money back. Give him his bloody money back, plus a piece of my mind. He takes umbrage, goes on the forum winging that I was rude to him. I reply with the full story, he gets it from all, he throws another hissy fit and he has not been seen since.
Have advertised some things that have attracted con men with all sorts of stories and strange places to do the deal. Easiest way of getting rid of them. Say sure will meet you at a police station, somewhere in the middle, and we can do the deal in the charge office. I hear no more. Another way, I tell them to do a real time EFT and I will knock the fee off the price. Silence.
Blokes who have found some 70's or 80's stack system originally sold by the furniture shops, then they try to pass it off as classic vintage at a stupid price. It were shyte then it is even more shyte now. Same with the assholes who try and palm off some horrible budget Japanese 1970's amplifier as a true classic at a price 4-5 times what the grainy gutless POS is worth. Sad thing is some dick falls for it and buys it.