As sports fans, we are predisposed to complain whenever "our team" makes a trade that involves a marquee player.
It's in our nature. We don't want to see our favorites walk away—especially if they're going to be wearing the uniforms of our rivals—so we complain, even though deep down we know the trade was the right move. Look at what's happening in Boston with the Celtics right now. Was it the right move? Yes, but still, the fans are still on the verge of rioting.
There are good trades that seem unfair at the time, and then there are really, really bad trades. I'm not even talking about the truly terrible lopsided ones (though a few of those made the cut for this list). Have you ever seen your favorite player exchanged for a fence? Or traded for a hunk of pork? Or traded for himself?
Yeah. When Paul Pierce and Kevin Garnett get traded for a bag of maple bats, then we can complain.