If I say, "Pineapple Pizza is good, " I think the safe and smart thing to do is assume it is my opinion and it doesn't require push back or attempted diminishment as "just [my] opinion." I think it makes the person who does seem kind of defensive and dim.
If I say, "Pineapple Pizza causes cancer," I think it is fair to push back on that because it is stated as a statement of fact without room for that being an opinion. Heck, even if I say, "In my opinion, Pineapple Pizza causes cancer," I'd still deserve pushback because stating that it is an opinion does not obviate the factual aspect of the statement.
All that being said, Snarf's posts are good but
might cause cancer.