Pond snails are kinda pretty when they grow up. They are excellent cleaners. I think since there are different kinds they could adapt to different tank parameters, but about half of the year my city water is around 6.4 and the other half it is 7.2- 7.4 pH, I don't know if that makes any difference, but although I have some pond snails, I don't ever have too many.
I am even an over feeder at times and don't have too many, though there seem to be more of them when I am over feeding. I don't use flaked food almost ever, which I think spreads out all over the place more as it disintegrates. Thinking that snails could eat more of that.
It seems they prefer harder water or don't like soft water. I keep Cuttlebone in the tanks for the inverts and feed Crab Cuisine which is good for shells of my intended inverts but that doesn't seem to matter as in causing over population.
Over feeding will for sure encourage more. I keep Ramshorn snails which I absolutely love. Here is one of my first ones I ever had in my signature.
Trumpet snails (substrate dwellers mostly), many are commonly known as Malaysian Trumpet snails or MTS, I guess I can say I have in great abundance.
I have native North American trumpet snails and MTS.
Partially it is personal preference, if they are good or bad. Some varieties will eat plants and if you keep plants. Not pond snails, Mystery snails or Ramshorns, only the decaying parts which is a big benefit.