66,000+ miles on mine with no issues. Headed for Austin and the MotoGP followed by a Hill Country ride. Just racked another 2500 going to Florida and back. For every tale of horror, there are dozens like mine. Two sets of tires per season, Oil changes every 5K with Mobil 1 4T. Valve clearance check/adjust along with throttle body synch and clean every other winter. I'm rather anal with maintenance, I pick the seals out of the wheel bearings and repack them with grease every tire change. Added a manual camchain tensioner even though the stock item was giving no problems. Oh, yeah, remove, clean and re-oil the air filter EVERY winter. I skipped a winter and my BMC filter was nearly clogged with bugs and dirt. I also clean and grease the inside of the airbox cavity (frame) each time the throttle bodies come off.
If you are buying used, check the chain and sprockets for wear and the clutch for operation. Listen to the engine idle and if it makes no disconcerting noises, it should be good to go. Chains and sprockets last 20-30K miles with regular cleaning and lubrication. I'm still running the original clutch.
It may be a pig, but it's a pig with a rocket in it's ass!