What happened with Schwinn? They used to make some decent bikes ages ago. They went under once, I'd hate to see the same thing happen... mainly because they were historically a mainstay of bicycling in the US.

Personally, I would just buy new from a known good brand if you don't know the provenance [1] of the bike you are buying. Of course inspect it, or have it inspected by a reputable LBS.

[1]: Make sure you have a copy of a receipt or whatever where the seller of the bike bought it from... life starts to suck if your bike gets confiscated by the local PD because its serial number is on a stolen list, and the seller skips town.