Gillespie was a good coach, but he was also clearly a drunk. There's just as much of a chance that he flamed out at Tulsa via his addiction as he was to succeed. Even then, that was nearly a quarter century ago. Most coaches weren't even out of college at that time and all recruits weren't born yet. Get over it and deal with the situation at hand.
I have very little interest in what an agency wants to feed me. Agents are the people who convinced our school to give Wojcik, Haith, and Konkol extensions rather than pink slips. Obviously most of (if not all of) these coaches will have representation, but if they're stuck to using them as a barrier to discussions on program philosophy then I probably don't want those coaches anyway.
We can of course discuss contract details through agents, but I would refuse to operate a coaching search via consultancies or agencies as a primary method of identifying and vetting candidates other than for background checks of the people I (as a hypothetical AD) identify.