Well,
My 2 love sand,a nd I just recently moved them to a tank with oak leaves and sand and I never see them, seem happy though. Mine eat just about anything, small snails, sinking foods, flake, whatever lands on them as they don't move much. Very nocturnal fish.
I've had good luck with mine, but be careful when cleaning the tank and vacuuming the gravel, as these guys will not move out of your way. I normally end up pulling them out of the gravel and putting them somewhere in the tank away from where I'm cleaning. They are so passive that I can move them by hand, and have never had them react badly, they also mostly stay where you put them, at least till the tank lights go out.
--Mia