[QUOTE=Muirenn;654128]Check the bike very carefully. Look for scratches on the brake levers and hoods that may indicate a crash. Look at the rear derailleur and check for scratches. Also indicative of a crash. Check the rear dropout area right over the cogs, this area can get worn if the low limit screw is off. If that area is carbon, could be a bad idea. Look over the entire frameset and remove the seatpost and look in the seattube for condition, cracks, etc. Look over the fork carefully. Look at the rear corners of the saddle for scuffs. Could indicate a crash. Yeah right, those marks happened from leaning against a wall. Sure they did. Everyone uses that excuse on used saddles on Ebay. Doesn't much matter for most saddles, except carbon ones. But does indicate a crash.

Check the general condition of the paint and try to imagine what caused any issues.

And, of course, ask if it's ever been crashed.

Thanks Muirenn - I always enjoy your posts so was hoping you would chip in :-) .... altho, now I'm not so sure as I think I'm perhaps naive or at least, too trusting. I had already asked if it had been crashed or laid down and when the answer was "No", I thought nothing more ..... until now!!! Hmmmm, you've certainly opened my eyes to things I never considered and for that, I'm most grateful. Will check the bike out per your instructions; never wouldn't worried otherwise but makes perfect sense. Just a couple of questions (as I've never bought a pre-owned bike before so am not used to this): I don't 'get' your point about carbon saddles - care to expand that?
Also, how does removing the seat post help my investigations?

Thanks so much again for your valuable insights - might turn out to be my saving grace :-)