Lets say there is a used S2000 in the market with 5K-10K miles on it. It is never driven hard or VTECed. Would you buy this car?

I personaly would not. In my books that engine is dead and would never perform the way it would compared to other S2000s. I have seen cars that are broken in and driven differently and would perform differently.

What would be the logical explanation to this if it is true?

 

I would and did. In my case, I saved a few grand and got a 100k b2b warranty in exchange for not having a baby s2k. I'm not really interested in the few extra HP a properly broken in engine gives, and since my girl doesn't drink oil it would appear that it was done somewhat well. If my intentions were to auto-x my car, or mod the heck out of it and go 'vette hunting, I may have done something differently, as the warranty wouldn't matter, but a few HP might...