I know there are some poisonous wells. But there are a lot of wells that seem to do nothing.

Is there any point to click on a well at all if most don't do anything and some are bad?

Been a long time but....

I seem to recall that there are a few wells that do have some beneficial effects (can't remember what, though). There is one well in Chapter 3 that actually has something you need. You need a key for it. (Really, can't complete the chapter without it.)

One of them has a quest item in chapter 3. You might find items in a few of them too.