I think most of the time they don't know what to say and "Hi how are you" to most people has been converted to a fairly shallow way of saying hello.

Maybe a few of the very close ones, you can go back to. They might be willing to watch for the "signs" - though it is pretty easy for us to weasel out of those too. Even if it is just one person who can actually ask - are you feeling down today? We may be able to somehow find the strength to nod yes.

I think the person who usually notices for me just doesn't want to go through the process again.