That's a great post and something I always think about.
I agree, the term 'team bike' in many cases should be 'team spec bike'.
I had a few bikes that have come straight from teams or people who source bikes from teams. Some you can tell are race bikes as spec is different to standard (brazed on race number holders etc) but difficult to say unequivocably. Bit different to old race cars where you'll have a chassis & engine number.
I remeber someone told me that there are more Manx Nortons motorbikes in existance now than were ever made by the factory.
as someone who has worked in the classic car field for the last 12 years I have seen 2 cars with the same chassis number both claiming to be the original one .