>> Tell me how to differentiate "this mage is screwed" with "this mage hasn't even made an effort".

I don't think you can know it for sure.
Probably zero observation/exploration points may tell that he hasn't even made an effort. But if he has lots of them there is a possibility (only a possibility) that he actually tried.

I also had a wild idea about some special kind of observation exp called "wands oservation exp". You gain those when you check actual or other "making-sense-wand-wise" locations. Like if you look at the archmage of Corte you gain some of those points along with regular observation points. This way the person in order to accumulate those points will actually have to check magical places/locations.
But I'm not sure if it will be worth implementing.