SQUINT hard, and textbook publishers can look a lot like drug makers. They both make money from doing obvious good — healing, educating — and they both have customers who may be willing to sacrifice their last pennies to buy what these companies are selling.It is that fact that can suddenly turn the good guys into bad guys, especially when the prices they charge are compared with generic drugs or ordinary books. A final similarity, in the words of R. Preston McAfee, an economics professor at Cal Tech, is that both textbook publishers and drug makers benefit from the problem of “moral hazards” — that is, the doctor who prescribes medication and the professor who requires a textbook don’t have to bear the cost and thus usually don’t think twice about it.