I just woke up and my brain hurts so I'll make an example:

Person A owns /ABC and has /XYZ on their wishlist; Person B wants /ABC, so they go offer for & successfully get /XYZ. Person B then goes back to Person A and offers /XYZ for /ABC !

I don't like this because if somebody wants something from me that I wouldn't do, it wastes both of our time. I would rather have people discuss it with me before they go around trying to obtain my wishlist URLs … unless they plan to just gift it to me.