Deception and the Number of Opponents in the Pot

With weak players, with a large pot, and with large early bets, you need not be so concerned about disguising your hand. A corollary is that the more players in the pot, the less you gain by disguising your hand. You cost yourself too much when you do. You won't be able to make everybody fold when you bet with a weak hand, and you cost yourself too many bets when you miss a raise with a strong hand. What's more, when you let many opponents in cheaply, you increase the chances of being outdrawn. Heads-up situations require disguising your hand more than do multi-way pots.
Let's look at two early-round betting situations - one in which you don't care that you've given your hand away and the other in which you should use deception. In both situations you have a pair of aces in the hole before the flop in hold 'em. That is, you have the nuts, the best possible hand at that point.
The first game is no-limit. You've made a small raise, four or five people have called, and now someone puts in a substantial reraise. You must reraise again even if your play gives away your hand completely. It is worth dropping all disguise because as the pot gets larger and larger, what's in the pot right now counts more than potential bets on later rounds. With two aces you should put in all the bets you can.
On the other hand, with two aces against a good player in a limit hold 'em game, you should often not put in all bets. A reraise is fine because you could have a variety of hands. However, if your single opponent reraises again, you should probably just call. If you raise one more time, your opponent figures you for two aces. All you have gained is one small extra bet right there, but you may have cost yourself two or three bets later on. In this case, you have lost too much by giving your hand away. You stand to gain more by using deception.