It depends.

A buddy of mine had his Ridley Excalibur stolen out of his car a few months ago. It has quite the unique setup (he built it himself from lots of random parts), but includes things like SRAM Red and tubular wheels. A couple months after it was stolen, a local bike shop sees this bike. The guy bringing it in wants to swap the Speedplay pedals for platforms. This seems odd, so the shop guys do some googling and find detailed blog entries from a friend asking people to look out for this bike. The shop tells the guy to leave and threatens to call the cops. My buddy gets his bike back with some minor scratches.

So while I see plenty of people in all kinds of attire on a wide range of road and tri bikes doing laps around a park on weeknights, sometimes there are red flags. Other times, who knows.