I guess I've gotten pretty lucky so far...my copper banded goes nuts when I reach for the food bowl(I scoop some water and then let the frozen mysid/brine thaw then serve) And as soon as it hits the water he's all over it...I think I over feed him...he looks nice and fat.
It's true about the emerald crabs I have two and I usually only see one or the other once MAYBE twice a week, they like to hide in the rocks all the time, but haven't bothered my cleaner shrimp at all...although I do wonder where his molted shell goes...
Horshoes are cool, but not when you step on em at the beach...and it's not soundin like it'd be a good idea for my tank either...
Keep the good advice comin!!