This may be a product of a bad example; it usually occurs when I have sufficient reason to not believe the opinion, and doubt my subconscious' influence.
Quite possibly. I don't have any experience with your subconscious. I still recommend keeping track of such things- they're a delightful way to learn about your mind. Remember the old joke about the gambler, who stopped writing down his winnings and losses because it was unlucky.
Recently I've noticed that, while introspecting, my internal monologue will state an opinion on a preceding thought, and I will feel an immediate repulsion towards that phrase as something disingenuous or alien. I will then recognize it as what I've come to term a "cached phrase". A variation/subset of cached thought, it is usually a string of words or that one might hear in a movie or something a friend or coworker would say, but comes to mind when you yourself are thinking about a domain associated with the conversation from the movie or friend.
Some (half fabricated) examples:
I wonder if it correlates positively to the OCD spectrum. I notice it quite frequently in myself (I'm not diagnosed OCD but suspect a slightly higher than average presence), and sometimes struggle to determine whether it's an opinion I truly hold, or if my hypothesis is an actual explanation for its appearance, or to what degree one of the two is true. Do I really feel what I think? It is too often ambiguous to myself.
Perhaps it is related to the concept of mentally modeling other people. We have our models of what other people would say in certain situations, but in this case, a random model's opinion is invoked involuntarily.
Does anyone else experience this? Do you agree with my hypothesis, or are these actually genuine thoughts; subconcious-level emotional reactions? Is there, or can we develop, a heuristic for determining where a certain thought or opinion lies on the spectrum between the two?