So for those others who don't catch up pretty quick, here's the first thing I found on google after searching for "opinion dictionary":

1. a belief or judgment that rests on grounds insufficient to produce complete certainty.

2. a personal view, attitude, or appraisal.

3. the formal expression of a professional judgment: to ask for a second Medical opinion.

So there you go, CP - 1. is an attempt to make a factual statement based on insufficient grounds, 2. is personal appraisal, or "attitude", that doesn't have to be factual in the first place.
I'm challenging the dictionary, though?

Already two completely different meanings. Passing an "opinion as a fact" would be two completely different things, depending on which meaning you're using. The rebuttals would have to be different, too.
In one case, you explain how the evidence or reasoning is insufficient, in the other, you get philosophical about subjectivity and objectivity, and how there is a distinction between the two main mental states, one of which is about knowledge of the external world, and the other about appraisal, values, and conceptions of how one's own ideal world might look like.

So which is it now? Have I passed a judgment as a proven fact? Or maybe stated my personal taste as a well-founded judgment? Or maybe I claimed to have scientific proof for how fun the remake of King Kong is?
Or have I just stated a well-founded opinion as a well-founded opinion, in contrast to someone else's poorly-founded opinion, and that got their feelings all hurt?

I'm waiting for examples. :D