I mean it depends on whether or not you like snails. People tend to refer to a pest snail as any snail they did not purposely add to their tank. The most common in the USA by a lot are bladder snails aka pond snails. They tend to lay their eggs on the leaves or roots of plants and then they hatch out in your tank after you place the plant.
Snails are not destructive to the tank, they will not eat healthy plants but they will eat the leaves of plants when that leaf is dying. This is what confuses a lot of people on snails. They see them eating a leaf that 'looks' healthy and they flip out. But the snail can tell when a leaf is dying way before we can. They also eat algae, left over food, and biofilm. Frankly snails are wonderful in aquariums. I purposely add blue ramshorn snails to all of my tanks. I also pickout the bladder snails from most of my tanks simply because I don't want them out competing my ramshorns ;P