Two people can perceive a given event differently. If your perception of it doesn't line up with mine, whose perception of that event is true? Now, we're not talking about people who are clinically mentally compromised. Those individuals need medical and psychological treatment, not legal counsel.
California Civil Jury Instruction number 1701. An opinion may be considered a statement of facts if said opinion suggests that facts exist. When deciding this issue, you should decide whether the average listener will conclude from the language of the statement and its contents that the person was making a statement of fact. Here's a statement of fact. Very few people understand what I just said, including myself.