in 200+ sales i've had 2 bad & 1 'meh'...
bought a 'sting' sword from LOTR... the official movie edition. It arrived. So I ordered 2 more, & three knives for daily carry. 1 arrived, the others didn't, & then the seller declared Chapter 5... Lawyers were guaranteed their $$, we buyers didn't get jack.
Bought a set of nerf bars for a blazer... 2nd time i'd done it, 1st having been great. Bars arrived without brackets. After being assured for 3 months the brackets were 'on the way' the seller was suddenly no longer on the site, & so i've got bars that i can't bolt onto my truck.
And got a lens for my nikon that fits but has ZERO in the way of communication with the camera... But they didn't claim it did.
Oh, two others...
bought 2 wireless keyboards separately... buyer wanted to use Western Union, BUT I didn't have to pay until after i'd received the merchendise, so i was ok with it... eBay wasn't, and sent warnings, AFTER I'd already paid... Corporate cya.
And this last year after i'd 'won' & paid for the 'P90X' set, they sent a warning that there were complaints the set was pirated & warning me not to pay. Of course, same seller & a host of similar sellers were still selling the same item. Fortunately it arrived and wasn't a cheesy rip off. BUT it's another example of eBay looking out for eBay & screw the buyers.
So my advice is always shop with sellers who've got experience, know what's a good deal instead of assuming what you read is true, & if it's TOO good a deal, it's probably not a deal at all!
That said, it's a great way to get stuff either unavailable locally or at a better price... I actually bought my motorcycle through eBay... it's not perfect but it's not evil or without benefit.
Pax, RA