Do suction cups stick equally well to different surfaces?
No. How well a suction cup sticks to a surface has to do with how will a seal can be formed on the surface. Rough surfaces will not form good seals compared to smooth surfaces which means that suction cups will not stick as well to rough surfaces as they do to smooth surfaces.
The liquid wetting the surface forms a seal that holds atmospheric pressure outside the suction cup. With a dry surface, air can leak through scratches and roughness at the interface between the cup and the surface causing the pressure inside the cup to rise to that of the surrounding air. Once the pressure inside the cup equals the atmospheric pressure outside, there is no longer a suction force to hold the cup in place.
octopus can stick to your throat while you are eating it but this is a very rare occurrence. not all sushi bars will cut off the suction cups and while you are ingesting the substance the pressure from your esophagus will cause the suction cups to retract and will stick. to get it off just drink some water or something
No toes. Mucus like qualities, and they both have adaptations that allow them to move and latch onto things, for example the octopus has suction like structures on its tentacles, and I believe the snails have very small lump like structures that allow them to move and stick to surfaces that are not flat.