Amazing how opinions differ:
Bimble bee snails: "Bumble bee snails are an ideal addition to the cleaning crew for any tank as they will eat any uneaten food, decaying matter and most algae species"......."burrows into your sand bed, consumes sand-dwelling worms, and helps aerate your substrate".........."relatively shy and is only seldom seen out during the day. The Bumble bee snail is easy to care for and quite hardy."
All I can say is that mine are doing fine and so are my other snails. I have 6 trochus, 3 Nassas and the 2 Bumble Bees. I saw all at the same time for the first time in months about 3 weeks ago about 2 hours after lights out...it was quite an occasion!