Pretty much I only see obs xp for using look or examine on objects, room description things and mobs.
Considering a mob may consitute a look though, just like loring an object may constitute looking at it, but I don't believe that considering or using lore are independent ways of gathering obs xp outside of using look/examine.
In other words, if I look at a legendary object and get nothing, I'm pretty sure loring it is not getting me anything either.
But if I lore it and don't look, I may get something as if I had looked at it.