I remember how I was blown away by this video a few years ago:
The word you are looking for is "sociopath". Oliver Wendell Holmes' "bad man" is an analytical tool, not a recommendation.
There's nothing inherently evil about the mood-detection feature you have described, provided it is deployed with continuing and informed consent from the user.
The feature is already deployed on billboards in public spaces, although this instantiation is evil as "users" are generally unaware of it, have not consented to participation, and cannot opt out.
> sociopath
ok, I mean no harm to humanity, but, um,
I don't think many people actually subscribe to that ideology, but enough do that it's worth challenging whenever it is articulated (as it seems to have been in your comment).
A facial expression ML model would be trained beforehand so camera data would not have to be collected, but only pushed to users along app updates, and content would be analyzed and encoded at server side to determine what users are to feel, along with hints to aid learning and correlation between different stories, all subconsciously and automatically.
As for what to do with a system like that...I don’t know, make boatloads of cash by forcing in-app purchases? Push your favorite but little known novels and comics? Make group of people I like by my specifications? Promote good posture, regular exercises and force people to look up? I wouldn’t want to use it so specific elected officials pass or resign, or world’s atrocities to become accepted...
Then I got bored. But could it have been something like this?