Depends on the species. Dwarves are usually good in planted tanks, they only nibble here and there. They use the plants more as cover than anything else. Marmorkrebs work well in mine, though they do like moving my moss balls around to create hides for themselves.
Species that have more carnivorous tendencies will likely ignore the plants as a food source, but may move, uproot or damage them. And species that like to burrow, dig, etc will have your plants floating at the surface in no time.