as far as bicycle related items there are 2 items I was disappointed with that came from ebay.
the first wasnt ebays fault, it was UPS. I bought this bike (my first roadie) it was "destroyed in shipping" and never made it to my house. I was re-imbursed.
the other was a pair of neoprene cycling booties. I ordered what I thought was the correct size but they were too small. I exchanged them for the x-large size and they just barely fit over my shoes. They are actually uncomfortable around my ankles and the velcro comes undone easily. I never wear them. Fortunately I used my "ebay bucks" for that purchase so no big loss.
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2010 Kestrel RT900SL, 800k carbon, chorus/record, speedplay, zonda
2000 litespeed Unicoi Ti, XTR,XT, Campy crank, time atac, carbon forks