......buy second hand bars? Not that I intend to, like, it's just that I've often noticed them on t'other channels classifieds.
OK, if they're unused, then, why not but if it's a case of "...only 18mths old, some scuffs and scrapes due to clumsiness/death wish. Only selling due to upgrade with Tugfest Wizzo Carbon Bars (O/S)", well, would you?
This is obviously a complete psychological matter, insomuch any other component is just about as likely to fail second hand, it's just the Handlebar have that Face/Stem interface thing going on which just makes it feel more risky.