Not in my experience. I believe the placement is random (in particular, that the distance from you to the Pokémon was simply randomized). It does "feel" like they're placed "in a way that makes sense", because the image is an overlay on top of camera feed - which guarantees it is on top of everything
in the camera feed, and the brain will play tricks to make sense of the picture. It works especially well if you don't have the feel for how big the Pokémon should be compared to the environment (most of us don't). See also, "perspective optical illusions" as a search keyphrase.
Also, again from what I remember when playing ~6 months ago, the Pokémon placement in AR mode locks orientation and distance. So walking forward is literally the same as standing still - only the background camera feed changes, but Pokémon and its animation isn't affected in any way. This again supports the theory that placement is random and totally unrelated to "real world".