There's no etiquette when it comes to side pots/main pots in ring games. If you think there is any profit in chasing someone out of the pot, you do it. If you made bottom pair or just have high cards and think you can bluff someone else off a similar or better hand, and by doing so even slightly increase your EV... do it. Tourneys are a different matter though. Eliminating players increases your EV most of all, so you always do whatever is most likely to eliminate the short stack - which often means checking when the sidepot is dry and your hand is weak.