I was recently asked if it was smart to bid up your opponent in a 4 player, set partner, rook game when your partner has passed and you clearly do not have a good enough hand to bid on. Notice, if your partner has already passed and you are the last one from your team in the bidding, you do not want to let your opponents off cheaply. Do not just pass to their early bids without giving a fight. It does not make any sense to give your opponents and easy chance at scoring some decent points without at least having to work for it, or having the possibility of getting set.
Personally, we have a standard bid we will typically go to with almost any hand. In our game of 200 pts per round including the 2s 3s and 4s, this bid is typically 145. Although this has fluctuated from night to night. Some nights the average bid is 155. Some nights it is 135. But most of the time, we are right around 145 on a base bid with marginal hands.
One thing to always keep in mind is your opponents could possibly be baiting you into bidding with powerhouse hands. On a number of occasions, to gain the advantage of a set, one of your opponents may puposefully pass early in the bidding wars to indicate they have a weak hand when in fact they have a strong hand and are likely to set you and your partner.
This all being said, bidding when you do not have a great hand is usually best when your opponents are about to win the game and you need to stop them from going out. You may sacrifice getting set for the opportunity that next round you will get dealt a monster hand that you could possibly shoot the moon with!