ridden hard and abused? stay away
serviced regularly and garaged a plus
look for worn perishables, oil leaks, small threads starting to stick out of drive belt, wheel bearings feel smooth, cosmetics in good shape, CEL on, overall feel for how the seller has treated it and how many owners has it had. i have seen xb9's with over 60K miles on them that have been religiously maintained and ridden sensibly and in great condition....and others with under 10K miles that have been abused and neglected and are junk.