That's a very vague statement

In the context of LessWrong it should be considered trivial to the point of outright patronising if not explicitly prompted. Bayesian inference is quite possibly the core premise of the community.

How exactly should one identify those expressions of stupid opinions that are relevant enough to imply that the rest of the author's work is not worth one's time?

In the process of redacting my reply I coined the term "Freudian Double-Entendre". Given my love of irony I hope the reader appreciates my restraint! <-- Example of a very vague statement. In fact if anyone correctly follows that I expect I would thoroughly enjoy reading their other comments.