personality vs illness

Question
Hello,  My sons and I recently bought 3 purple pinchers (PetSmart) and are keeping them in a large plastic rubbermaid like container with several inches of baked play sand, an area of coconut fiber substrate, climbing fiber walls, a hut for each, fresh and salt water "pools" (one ceramic, one the stone-like kind), water is the pet store bottled crab water, crab pellets and "cookies" and a tiny bit of greens and carrot for food served in a clamshell, and about a dozen boiled shells from a craft store (snail, murex and conch-like of sizes from slightly smaller to slightly larger openings than the crabs are in now) and a little coral for good measure.  I bathed them all when we first brought them home but not since.  Kermit is very gregarious and rarely feels the need to pop into his shell, he will walk all over our hands and arms and pretty much anywhere we let him go.  Spike is a bit more shy but within several seconds of being picked up will come out of his shell and walk around, not as active in their home as Kermit but still active.  Telly however has me worried.  He was the only one who didn't come out of his shell to see what was up when he was bathed, it took him a good ten minutes to poke a bit of leg out at all and many more before we could see his feelers twitching around.  He is in a turban shell and pulls very deeply into it often, compared to the other two it seems oversized. I've added in smaller and lighter weight shells just for him but so far he hasn't changed.  If I hold him in my hand after many minutes I can feel him feeling my palm, not pinching, just tickling almost and eventually he will poke out from under the shell and look around but he never comes out as much as the others nor does he seem at all active.  He's so skittish I haven't even been able to glimpse enough to see whether he even has all of his legs, but from what I can see he does not appear to be molting nor has he shown any inclination to dig at all.  Could this just be Telly's normal personality?  How would I know if he is sick?  Thank you for your help - I'm drawn to underdogs and would feel awful if anything happened to Telly!

Answer
Telly sounds a lot like my Shyguy (aka, Shadow) only Shadows even worse, he would actually let himself drown if I didn't take him out of the bath, he REFUSES to come out of his shell no matter what I do, but if I have the room light off and am laying in my bed across the room, in the bloacklight glow of their heat lamp, I see him slowly and carefully come out of the hut and sneak around to do his crabby daily chores. Kermit sounds like my Gonzolez (aka Speedy Gonzolez, or Gonzo) He was named because when I was picking him out of the tank at the petstore, the cashier put him on the desk to get another for me and we turned around to get him and he was almost running off the edge of the desk, we caught him and put him in a cricket cup for the moment. Hermit crabs, in their own simple way are a lot like any other animal, they all have their own personalities and their own quirks. As long as Telly is able to get in and out of his shell properly (at all, not all the way, no enthusiastically, etc.) just AT ALL, he is probably fine, a crab that is unable to get out (i.e. stuck) or one that is listess and won't go itno the shell or eat or move or do ANYTHING is sick, what you have is just a little shyguy, and he may come around with gentle treatment, or he may end up like my shyguy, whom I have had for over a year with absolutely no progress in the friendliness department, they are still fun to watch and although he isn't one I can play with, I enjoy owning him because his stubbornness just adds to his charm.