Objection 1. It would seem that every pleasure is good. Because as stated in the I, 5, 6 there are three kinds of good: the virtuous, the useful, and the pleasant. But everything virtuous is good; and in like manner everything useful is good. Therefore also every pleasure is good.
Objection 2. Further, that which is not sought for the sake of something else, is good in itself, as stated in Ethic. i, 6,7. But pleasure is not sought for the sake of something else; for it seems absurd to ask anyone why he seeks to be pleased. Therefore pleasure is good in itself. Now that which is predicated to a thing considered in itself, is predicated thereof universally. Therefore every pleasure is good.
Objection 3. Further, that which is desired by all, seems to be good of itself: because good is "what all things seek," as stated in Ethic. i, 1. But everyone seeks some kind of pleasure, even children and dumb animals. Therefore pleasure is good in itself: and consequently all pleasure is good.
On the contrary, It is written (Proverbs 2:14): "Who are glad when they have done evil, and rejoice in most wicked things."
I answer that, While some of the Stoics maintained that all pleasures are evil, the Epicureans held that pleasure is good in itself, and that consequently all pleasures are good. They seem to have thus erred through not discriminating between that which is good simply, and that which is good in respect of a particular individual. That which is good simply, is good in itself. Now that which is not good in itself, may be good in respect of some individual in two ways. In one way, because it is suitable to him by reason of a disposition in which he is now, which disposition, however, is not natural: thus it is sometimes good for a leper to eat things that are poisonous, which are not suitable simply to the human temperament. In another way, through something unsuitable being esteemed suitable. And since pleasure is the repose of the appetite in some good, if the appetite reposes in that which is good simply, the pleasure will be pleasure simply, and good simply. But if a man's appetite repose in that which is good, not simply, but in respect of that particular man, then his pleasure will not be pleasure simply, but a pleasure to him; neither will it be good simply, but in a certain respect, or an apparent good.
Reply to Objection 1. The virtuous and the useful depend on accordance with reason, and consequently nothing is virtuous or useful, without being good. But the pleasant depends on agreement with the appetite, which tends sometimes to that which is discordant from reason. Consequently not every object of pleasure is good in the moral order which depends on the order of reason.
Reply to Objection 2. The reason why pleasure is not sought for the sake of something else is because it is repose in the end. Now the end may be either good or evil; although nothing can be an end except in so far as it is good in respect of such and such a man: and so too with regard to pleasure.
Reply to Objection 3. All things seek pleasure in the same way as they seek good: since pleasure is the repose of the appetite in good. But, just as it happens that not every good which is desired, is of itself and verily good; so not every pleasure is of itself and verily good.
Source: Summa Theologica (New Advent)