Agree, there is a highest bidder, usually, on every property as evidenced by the multiple offers that far exceed the listing price and the prevalent market values. IMO, that 'winning' bidder often exceeds the market value. Again, the concept that just because someone is willing to pay $X for a property automatically means that the property is worth $X would result in a lot more appraisers being out of work.
If one bidder at an auction overbids the local market value, I'm not inclined to accept as fact that its worth it, whether its the subject or a comp.