The final "ethical" fantasy question I can think of is a personal pet peeve of mine. We've all been there: we're in the fantasy finals, and we're tempted to start adding / dropping players via the waiver wire, cycling through the weakest players on our roster to guarantee a games-played advantage. This way, you can guarantee that you have a player playing in the "cycled" slot every night.
Is this acceptable? I personally think it's a bit sleazy, and can't stand it. However, I understand the desire to win, and think it's up to commissioners to set rules against this behavior, by limiting the number of add/drops during the playoffs.