Pedro,
I use them for a few items. Cherrystone clams are often nicer quality than I/S although not always.
Good prices on 5# boxes of frozen shrimp such as 16/20 ct. and also on the various grades of canned pasteurized crabmeat from SE Asia.
I've only occasionally seen fresh finfish like sole, trout, etc... could be that's kept in another cooler or perhaps they deal primarily in frozen.