Odo meter could be clocked BUT a sure sign of high usage is the wear on the pedal rubbers, steering wheel (of course a cover may have been used!) and horn button area, and shift lever knob, light and wiper switch markings. Usually no one bothers to change the pedal rubbers shift leaver knob and wiper and headlight leaver marking even if they wind back the odo!
A car with excess of 100,000kms will have worn out pedal rubbers whereas a car which has done a genuine 30,000ks will have the pedal rubbers almost intact. So if you see a car with 50,000ks BUT with worn peddle rubbers, erased light switch markings and a worn out sfhift leaver knob, it's a sure LEMON!
Just my two cents worth from experience!