For example, I've already harvested a peat bog, yet every time I go by it, it lights up blue and of course I think I can still dig in it. But I can't.
It would be really helpful to have a visual indication that no further resources where to be had in such cases. (Jellisacs and barnacles change appearance when they can't be harvested, which is great.)
This could also work for trees that don't want watering or petting and can't be harvested.
Basically, don't make me check over and over, please!