Look for pitting on underbelly and under mirrors. Also scrapes on clutck/brake levers and broken off feeler pegs. If it's there, the bike was dropped at 0 mph or fell of stand. No big deal, but you could use to negotiate.
I would want to inspect the outer housing of the steering stem for cracks or wrikles. That could result from dropping out of high wheelies. Check to see if the clutch fully disengages at a standstill in first gear. A slight jump and loud clunk switching from N to 1 is normal but if it wants to steadily creep forward with clutch in, there could have been a lot of high rpm launches done. I've heard some synthetic oils will cause the clutch to slip in the same way, though.
I've heard of several people complaining about brake squeek. Mine does it on light braking especially in the colder weather. I wouldn't be concerned about that.
If the tire is still stock, the bike was probabley not run too hard. Look at the tread. I'm at 6600 miles on my stock tire and I still have another 700-1000 miles to go on it before the tread depth is down to 0 on the center. If you see a stock tire with some life left, you know the bike was not run hard. How far back is the axle for chain adjustment? Mine is at the third mark from the front and I have done aproximately 3000 urban miles in stop and go.
If you get a good deal, I wouldn't shy away from a bike that has been run hard. The only problem I hear about is throwing a rod from doing long 12 o'clock wheelies and you obviously wouldn't buy a bike with a hole in the motor. I think almost every one of us has burned some rubber, done some little wheelies, certainly done some hard revs. I've done all that stuff. The bikes run good. They will take a lot of abuse.
Rook
'08 MIDNIGHT SAPPHIRE BLUE Now Deceased