For my 2 turbo snails, so far so good for eating algae on rocks, but they do knock off my frags and poop quite a lot.
For Nassarius Snails, they burrow in the sand, clear detritus and uneaten food but sometimes they leave a trail of slime.
After getting a saltylight foot crab, i prefer crabs than snails they are nicer to look at and hardworking at the same time.
For more established tank, you can consider starfish too.
I personally find that get a few types of clean up crew for my 2ft nano, i have 2 turbos, 3 nassarius, 1 satly light foot crab, 1 sand shifting star, 1 cleaner shrimp and 1 peppermint.