Yeah, I don't think a double-century test ride is in the works for a used bike purchase from Craigs list. Maybe a spin around the parking lot to make sure all the spinny parts spin. You shouldn't need to fork over a ton of money to go 50 yards on the bike to make sure it works.

However... if you want to buy a used bike, you have to have the cash. You can't say "Hey, I'll get the cash tomorrow if I like the ride" because that doesn't work in used sales land.