eBay and Craigslist finds

I don't think so, people that steal bikes are not likely to post up such detailed pictures.
Always, always insist on buying from an address and not from a tube/train station, and if the guy calls you back on a withheld number, it's a sure sign to back up.
I make sure I get receipts too if I buy from Gumtree.

good luck with going to an unknown address with money in your pocket.
always use public spots people...