Are super worms considered CUCs?
No, but there is a Darkling CUC.
The "Litter Beetle" and their larvae "Lesser Mealworms", are CUCs. There is a couple others I think.
Skull eaters? Y'all talking about Dermestidae (Dermestids) beetles right? AKA as Skin beetles / Buffalo Beetles, because they will feast on Human Skin, and Devour an entire Buffalo.
They are flesh eating Scarabs and will clean bones perfect, like Night said. Lots of people use them as CUCs for roaches and the like. I would never ever put them in a Viv with a Cham though.
They are also heavily used in museums and taxadermy to clean bones.
Larvae look like a hairy caterpillar, Beetles are just small Scarabs.
They do not mess around.
I don't use them personally, as they are dangerous. If you forget feeding or 2 and they run out of dead roaches, they will kill and eat live ones. Don't feed them for a week, and stick your hand in there and they will nibble your hand. If they get out of control, it can cause issues in your colony.
Isopods, will eat dead and only dead things, and eat poo and whatever you feed the roaches. They will not try to eat live roaches.