So how does this interact with an illusion spell like Mirror Image?
Clearly with BlindSight, the Mirror Image is useless. But LifeSight only detects living vs. undead vs. construct and I'm not sure how illusions interact on that level.
So I guess the key is whether these images would be perceived as "living", "undead" or "construct"?
Does the answer change for something stronger like Major Image?
Update: to clarify, it's clear that something like "blindsight" would bypass mirror image because mirror image is a visual illusion.
What's not clear to me is whether the illusions from mirror image emanates a "lifeness" or not. It's not detailed in the spell, but I'm hoping it would be detailed somewhere else in text about illusions.