Agree with everyone that a compression test is in order. And just because you don't see physical damage to the head doesn't mean there isn't any. Vehicle could have been overheated and warped the head, which would allow coolant to be burned as well. Keep an eye on your coolant reservoir too.

Or, if it's been sitting a while, maybe the guy that sold it to him thought he'd be nice and run some Seafoam through the intake right before he sold it just to be nice and it's taking a while to clean out......did that with the carbs on my bike and it took like 10 minutes of reving to clear out all the white smoke from two tiny carbs. That's kind of a stretch, but a possibility I suppose.

I don't think so. Just do a compression test and try.

It could also be to much fuel, is there a strong smell? But if not its a HG