[Exhibitman]

Or what we all should behave as if we were...

The issue of whether a bidding partnership is collusive is a close one [my experience is that the partnerships generate higher bids overall by pooling resources on the lot] but entirely irrelevant. Gentlemen do and do not do certain things not because they are enforceable contractual obligations but because they are the right things to do when interacting with other gentlemen. A gentleman:

--honors his wagers.
--keeps his word.
--watches out for his friends
--never cheats his co-venturers.

I partner with others on auction lots all the time. Never had a problem so far. Is it enforceable? No. Nor would I try to enforce it if the bidding partner decided to renege. I figure once someone gives you a cheap lesson about who he really is, choose to believe it. If a member here chose to cheat another member and it is clear-cut I'd favor outing him and then suspending him for a time. Might not teach the offender anything about how to behave but it would prevent others from being harmed. That said, it is the OP's choice whether to do so.

I have heard of certain members here whose word is no good on deals such as the one referenced in the OP and have refused to partner with those people on auction lots. Whoever it is this time, don't think for a moment that word of your behavior won't get around off the front page, so to speak, and that there won't be consequences to it even if the OP refuses to out you here.