You mean besides the girl behind the wheel of a bimmer.....
Just kiddin bro.....just drive the damn thing and if you have any testosterone youll know if its right or not. More often than not if you have been driving enough....all you need to know about a car os to get behind the wheel and drive a few miles. Besides that do a VIN check.....www.bimmerforums.com
has a thread going where a guy uses a software to tell you your VIN numbers history. Its under E-46 section of the forums. Its free but may not last long.
Obvious lemon indicators should be looked for.....obvious paint covering (yes i have seen people do that to cover minor scratches).....look at tires and brakes......(almost 2000$ if you have to replace them as soon as you get the car)....! Besides that dont forget to have sex inside a bimmer......always rocks.....especially if its leather.....:lol: !