I was a member of the snail avoiding brigade for a long time. Plant quarantine and dips and everything to avoid them. Then I started maintaining a little planted shrimp bowl and couldn't get control of the algae situation. Such a small system. So I went to the store and bought a little bitty gold snail to go in there. He was so little, he would surely do fine in a 1g bowl. Oops.
Now I have two of these gold apple snails (trap door kind, the ones that get golfball sized) and they've been moved to my planted forty gallon to be the heart of my clean up crew. They are always in motion, cleaning up dead plants, missed food, and even algae. They're surprisingly pretty.
They love the days when they get bits of blanched sweet potatoes (discovered this when feeding a BN pleco and found the snails on either side of the slice just going to town). I must have lucked out and gotten two males as I haven't seen any egg clutches in the many months I've had my mighty golden duo. They're about golfball sized now, but still manage to climb up my vals. Of course the vals bend when they get near the top and the snails just ride the plant down.
When shopping for apple/mystery snails, I specifically look for the trap door so I know I'm not getting anything that will reproduce on it's own or that will get massive. I don't trust the people selling the snails to have a clue that they even come in different species.
One word of warning to the betta owners: Bettas like snail antenna. They must look like little worms or something. When I first introduced my betta imbellis to my big tank, they immediately nipped those lovely antenna off of my snails. Since then, my snails have learned to duck and cover when the bettas come snooping around. I still won't put my nerites in there since they're so much smaller. I keep them in my shrimp/Endlers tank. They're much safer in there. I also don't keep a snail with my very active, hunting veiltail male. He goes through ghost shrimp like candy and I don't want to think about what he'd do to a snail. He's learned to leave the otos alone (they're faster than him), so they serve as algae control for that tank and the ghost shrimp do clean up until their luck runs out.