I likely don't know, and maybe that's OK. Shrimp cocktail is not high on my list of things to eat anyway. I can't remember the last time I ordered one out.
When we go to Hilton Head, we will hit the oyster places that have their own boats, and they do a pretty good job, my wife still claims they are better in Brittany. I can tell some difference in oysters, and of course, one can stumble across pretty bad ones.
I do like crab legs a lot, haven't had them in eons either. Back in the day, I'd look forward to a trip to Florida for FRESH fish, but it seems now everything is frozen. I had some fresh walleye a few times and it is incredible (not in Florida!). I've had fresh grouper in Florida that was outstanding, but not in decades.
A friend once told me that raw oysters were just an excuse to eat cocktail sauce, but I've learned not to use that on good oysters.