That's the problem with espousing the philosophy that only collusion is a reason for a veto. If one manager's lack of knowledge creates an opportunity for teams to improve through obviously lopsided trades, you run the risk of one manager getting an extra 1st rounder.
It shouldn't be incumbent on every manager in the league to offer lopsided trades at every opportunity until they finally manage to ruse a noob. When trades come pending that are wildly lopsided, there has to be a point where you say enough is enough, if only because you can't prove collusion in the first place, so a wild difference in value is some circumstantial evidence for collusion.
Sure unbalanced trades will go through, but you HAVE to draw the line somewhere.
Just look at this thread and try to tell me that this guy's league isn't ruined because of what he got away with.
http://www.fantasybaseballcafe.com/forums/viewtopic.php?t=280459&highlight=
I used to hate vetoes too, but protecting the integrity of the league should be at least important enough for a league votes veto system.