I disagree--our not being ball pythons does not mean we cannot observe behavior and make logical inferences. If a ball python willingly accepts PK prey, and refuses heated FT, obviously it detects a difference between them. That is something we know, and we do not have to be ball pythons to know it.

Which they prefer is more subjective. Based on behavior, most ball pythons prefer PK to FT, but some prefer FT to PK.