To me, plopping star players (regardless of the reason) is playing to lose. You don't put your best team on the field, it is playing to lose. If you are putting a guy on the farm because a deal is pending, make an announcement. Simple enough to do. That way, you appear above board to all the other owners in your league.

A neat trick I've got a hunch about (wish I could prove it) is dealing a lot of your players for rookie and free agent picks, then reallocating your team to get more players from the realloc pool. Again, *not* against the rules. Just not really *sportsman* like. It is, after all, a game.