The first one I ever tasted was in Cyprus, where an octopus attached itself to my bare white heel , as I was preparing to dive. My companion picked it off, bashed it on the rocks where we were sitting (to tenderise it), and told me how to cook it in slowly in red wine for a very long time (with the usual extras).
Octopus cooking is a very delicate art; it's one of my long-term projects to learn exactly how.
Blanch, raw, slow cook, rapid boil, or what?*
Somewhere along that gradient, there's a point where the meat will come out fresh, tender and tasty. That's the moment when the real cook will know he's got it just right.
I'll keep trying.
Meanwhile, consider these poor octopi, who are extremely good at doing camouflage, but have been wholly confused by being put out to expire on a chequered background.
Update 1: The answer to this is to get the first cooked point just exactly right, or stew the damned things for hours to get back to it.