Aslan, I consider a ploppy to be someone who is not skilled in blackjack. Someone who has studied basic strategy enough to know it cold is in my definition is skilled as the casinos have a much smaller edge over them than someone who has not studied at all. In fact, the casino often times does not make any money off this person due to comps, etc.
Knowing BS, does not necessarily make you an advantage player. However, with comp hustling, scavenger play, dealer mispays, etc, this skilled player can in fact be an AP.