[munificent]

The problem with that is that doing a thing that carries its own intrinsic value forms a poor signal because you can't tell if someone is doing it for signalling reasons or intrinsic reasons.

If you decided that a hallmark of your tribe is brushing your teeth, then when you see someone brushing their teeth you still can't really tell if they're in your tribe or not.

The best signals have either neutral or negative intrinsic value because the more costly the signal is, the more likely someone doing it values the signal.