As mentioned before, Vampire plecos are carnivorous (though some veggies in their diet is good), and don't typically graze on algae. Plecos will scavenge for uneaten food at the bottom of the tank (some more actively than others). But the bio-load they produce outweights any benefit from "cleaning" I would say.
I keep plecos because I like them
not because I expect them to do anything.
No experience with snails...but I believe Vampire plecos are leporacanthicus, which specialize in eating invertebrates if I remember reading right (from the pleco dietary thread in pleco forum). So, those snails might just end up as increased bio-loads from your plecos
I keep plecos because I like them

No experience with snails...but I believe Vampire plecos are leporacanthicus, which specialize in eating invertebrates if I remember reading right (from the pleco dietary thread in pleco forum). So, those snails might just end up as increased bio-loads from your plecos
