The interesting fact supporting your point is that Pacmans are opportunistic feeders. Identifying a time an animal with this quality is "hungry" or "needs" food is hard to do because in the wild they feast when food is plentiful, or eat as long as food is present. Once food is scarce they have to subsist on what they've accumulated. Of course, we obviously see instances in which opportunistic feeders do not appear to want more food/seem more enthusiastic about it. Factor in the fact that they're cold blooded and have a metabolism tied to external temperatures and I think it's safe to say pacmans and other opportunistic feeders reflect how little is known about herptile nutrition, at least in the hobby's body of knowledge. It's easy to gloss over the fact that herptiles function based upon instinctual drives for survival in ways very different than say... a dog or a guinea pig as you mentioned.
I absolutely agree that a lot of new keepers can run into challenges tied to a first experience with the animal or the hobby.