What is the worst experience of "Planks" you come across while using eBay?

I put my LX 10 telescope up for auction, mint condition took a close up of the corrector plate to show how good its condition was, got an email from some prick telling me he'd offer 300 quid because the corrector place wasn't aligned! i told him if he was able to tell if a corrector plate was out of alignment (even though its fixed in position and can't be altered) just by looking at a pic he should be working for NASA. I pulled the action and then closed the account after i started getting "emails" from ebay and pay pal demanding money for an unsettled bill and wanted by bank account number, even though i already paid them legitimately. The real planks are ebay and paypal allowing scammers to get on the site and not having trustworthy staff