I feel like I am in a fricken Econ class....
I don't think that a lot of colleges look at it that way. Colleges are abreast of kids behavior and past transgressions when they recruit the kid. If the kid qualifies academically he is in. This was the old sentiment at
OSU under Coop. and Conley this is largely the sentiment across the NCAA D I football as well.
Many argue that Tress. now limits and approves each player before they are extended a formal offer. Many stated that Tress. was putting "unreasonable" limitations on recruits that handcuffed the coaches when compared to recruiting rivals. Parenthetically, people offered this is the main reason that Conley stepped down, however it could be speculation as well.
Does their marginal utility outweigh their cost? I believe that it does but it has to be taken player for player. Clarett is an example as you pointed out. I believe the coaching staff knew what they were getting into but I don't believe they knew he would be as good as he was. Moss would be looked at the same way. Obviously, Guilford' wasn't but others were. Every school excerises this right and I believe that we should as well but that doesnt look to be the course.