I don't know what the 'fish taste' guy is talking about. I have been eating John's stuffed shells and manicotti for several years now, and they are the best store bought pasta products that I have found. I live in Colorado and get them at my local butcher. In fact, the reason I am online is trying to find out who else carries them locally, as my butcher is not good at keeping them in stock.
I don't claim to know the best way to cook them, but being a single guy I am all about quick and easy, so here is what I do: I pour a little sauce into a glass bread tray, and then put in either 2 manicotti or 3 stuffed shells. I cover with foil, and then cook until the sauce is just about to boil (like 20 minutes). For good measure I'll drizzle on some olive oil afterward.