I'm beginning to think that if you are in a cave/wherever with wild Pokémon, are standing ON a ladder, and you take a step to go up/down that ladder, it does NOT count as a frame advancement in an area with wild Pokémon. After all, the spot ON the ladder is not a spot where you can find wild Pokémon (if you try to Sweet Scent there, it does nothing, but if you take one step back, you're fine). Can anyone confirm or deny this?
I ran across this by saving one step before the ladder to the rooftop in Tin Tower. I used Sweet Scent, caught the Pokémon, took two steps up (the first put me ON the ladder, the second one put me up the ladder onto the rooftop), ran up to Ho-oh, and caught it. I expected the Ho-oh's frame to be the "actual" frame of the Sweet Scent, plus 3 (2 for taking the two steps on 10F + 1 for Ho-oh's frame) or 4 (3 + 1 if the 128-step counter is tripped), but it was only 2.