as there aren't two teams colluding together to make lopsided trades (i.e. "let's trade all my good players to your team so you will be guaranteed to win the league"), I am of the opinion that all is fair in trades. If the league is worried about others being taken advantage of in a bad deal, then they should institute a trade veto ability where the league members can veto your trade. But besides that, I would have no problem getting the best deal you can in a trade. If somebody gets screwed over by it, then they need to learn how to play the game better.