Agree. There is an article (don't know if espn or SI or what) titled Meet The Bagman that describes what you are saying. The coaches and AD are willfully unaware of the activities, and the bagmen are smart enough to keep everthing untraceable. If a kid ends up with a car, and if the NCAA looks, there will be a bill of sale to the kid's uncle, dad, whoever.
The article descibes a network of small money guys. The million dollar givers buy weight rooms. The guys with 10,000 to spend do bag work. They are careful about money not changing hands, about meetings not taking place directly, etc. The photos one sometimes sees of bling and cash are not from the bagmen; they know better. Those photos are just kids being kids. The bagmen are pretty skittish of people who want to get in to meet athletes, feel important, etc. They are committed to 'helping' (if one can call it that) a program while remaining anonymous to nearly everyone. They never meet a coach, rarely meet a player. There has to be a moat between what they do and anything related to the program, cutouts between cutouts. Most coaches might even be surprised at the level of this activity.
A coach cannot oversee what millions of fans do. All he can do is preach ethics and then instll those ethics within what he can influence, which does include the boosters and booster clubs. But if some no-name in Hartsville makes sure a kid's uncle has enough money to buy a car, no coach wants to even know about that, because once he knows he has to do something, and he can't do everything or control everybody. And to be honest about it, as much as I hate to say it, that is probably outside the NCAA's legitimate jurisdiction, and should be. When basic morality fails, you can't control everybody.
I am totally with you in your feelings that this ruins the sport. As important as the sport is, its just football, and when it becomes an enterprize with no boundaries its just not fun anymore. The only way to keep the fun is to assume one's school isn't doing it because the coach maintains a clean program. Intellectually we know its more complex than that, but allow ourselves a fantasy of cleanliness.
Enjoyed the read. I would guess that NCAA Division III and the NAIA don't have bagmen (bagpeople?) lurking beyond the shadows. Or am I being naive?