Few bikes will come with a known history. Does it start easily? Does it seem fuel starved when cold and run better once its really warm? If so you better have a talk with the Doc (Guy Clark said that I didn't). Seriously, when intake valves get tight, you start seeing symptoms. Valve clearance is one of the things you'll do once you have the bike. But once done you won't do it very often unless you are compulsive.