Eh, I dunno. I have posted stuff up for sale untested for two reasons: first because I couldn't be bothered to test it, and second because some things people will go ape-shyte over if it is tested and prices will go stupid and blah blah blah.
Anyway, sometimes I just don't want to or don't have time to. In my case, however, there's a much much higher likelihood that it will work. The rare exception will be something which I bought and wound up never using.
Buyer beware. Hell, I just picked up a Geneve at the TI Faire which the guy didn't test but I got for a steal.