[feocco]

I'd agree with the oddness of sharing your emotions in a team meeting. I likely wouldn't express my "true" feelings.

I gauge my teammates emotional states based on personal interactions and available context. Nor is it something I would want tracked. But perhaps kept in mind when adding tasks to their plate.

If you want honest feedback, I'd say use the power of anonymity. Engagement surveys with the right questions can pull this data. Keep in mind that the emotional statements can be hyperbolized one way or the other.

TL;DR - talk to your people "face to face." And reach out to those they're close with if concerned. Or directly and up front. Which avoids complicating with subversion.