Caveat: my current self absolutely hates my smug-ass teenage self that I used to be so I may be a bit pessimistic about other teenagers :)

I think you are. I agree that some teenagers love to feel smarter than other people (not necessarily their parents), but I hypothesize that this is more because no-one is offering teenagers the actual tools to be genuinely smart/intelligent. I think that there's a number of teenagers who, if they knew it was an option, would want to actually think hard and be smart without being smug about this. I'm not a huge fan of labeling all behavior as "signaling," but I think that the smugness and the wanting to appear smart is a substitute for the unknown option of actually being smart in a meaningful way.