It is assumed that most post on FR are opinions, with no disclaimer required, unless the poster goes out of his way to insist he is not stating an opinion but a fact, in which case he will be challenged to produce evidence for said “fact” or retract the claim. Opinions don’t require proof, truth claims do.
You didn’t simply fail to offer an opinion disclaimer, you made a truth claim.
>>. Opinions don’t require proof, truth claims do.<<
And the arbitrator of a “truth” vs. “opinion” claim is exactly whom?
And, I note your truth claim of “Opinions don’t require proof, truth claims do” is unsubstantiated and thus requires an “opinion” signpost.
The bottom line: You can’t win this one (I M H O). Every opinion is an opinion, whether it be declarative or sidled-up-to.
If a statement such as “Mrs. Palin is unelectable” requires me to signpost it as an opinion, I have a solution (see tag). Of course, to meet the ill-defined requirement of “opinion vs. truth claim” everyone else will need to apply the same solution.
Sadly, we will lose some very clever taglines, but forensics is a harsh mistress.