What is the best kind of stink bait for cat fishing during the summer??

One of the best, and least known, stinkbaits is rancid chopmeat.

I once watched an elderly gentlemen literally fill a stringer, in the daytime, fishing for cats with that bait. He'd mold a ball of it on a treble hook and freespool it under a large bobber.

If you watch the sales you can usually get a good deal on chopmeat just before it passes the use-by date. Freeze the bulk of it in fishing-trip size quantities, and take one out a few days before actually going fishing, leaving it out to both defrost and turn bad. Or, alternatively, let it go bad first, then freeze in trip-sized amounts.

If you want big catfish, though, stink baits are not the best. Trophy catfish actually prefer live bait (bluegill are popular) or cutbait (shad, skipjack).