When a monster is standing on an item, the mouse-over tool-tip reveals the item information, not the monster's HP and (de)buffs. It'd be especially handy for bolt-flinging Rogues if it'd be the other way around. Arrows will be strewn across the floor frequently, and nobody wants to waste an expensive steel bolt on a 12 HP monster when a plastic one will do. This may have been done intentionally to add to the difficulty? It seems a bit arbitrary, if so, though. Monsters can be incredibly tough and the game-play unforgiving, but at least that's in function of the game-play itself.
This is definitely a good idea. EDIT: Also, on a related topic, deal monsters should appear ABOVE floor engravings, not below them.