DougR:But when somebody says, "people ought not to do X" what could they possibly be doing except expressing an opinion? Unless you know of some source of objective, universally-agreed-upon "oughts"?
If on the other hand someone says, "my religion says people ought not to do X" or "Time Magazine had an article recently that said when people do X, Y happens" then they are obviously passing along a fact (or falsehood) about something, which one could conceivably go and check out against the source. (Unless their religion is so small there's no way of figuring out what it officially believes, of course.)
If someone says, "In 1520, Joe X killed Bob Y" then you can go and check it out. It's a matter of historical fact. But "oughts" are not a matter of historical fact, and there is no place we can go (that we all agree upon) to check out what one ought and what one ought not.
Thus it seems obvious to me (call me a weirdo) that when someone posts something in the form of "Doing X is wrong" that they are posting their opinion, and adding "IMO" is redundant (if harmless).
That said, people who say "People ought not to do X" but really MEAN to say, "according to the Bible/Koran/Bhagavat Gita/Rede/Whatever, people ought not to do X" should probably be kind enough to spell it out for us.
But of course they don't, so maybe that's your point? I'm willing to be enlightened. :)