This is only my experience. I am a retired satellite player from Florida and trained with Butch at the Down Under Tennis Club in Tampa day in and day out from 1990-1993. I was one of the only male tour players he coached. I was on the trip on which we warmed Navratilova up for the Hilton Head event. And yes, it was ONCE at Bolettieri's that we trained Borg indoors. Jimmy Brown and Kelly Evernden were also there.
At the "Hard Work University" as he named it, we were training the young Lindsay Lee, Stephanie Nickitas, Marissa Catlin, etc, all young attractive underage females. He did have 1 or 2 favorites but the extra attention recieved was all on court. I never saw or heard anything remotely resembling inappropriate behavior EVER, and I would have absolutely known about it. We were there from dawn till dusk. These girls were delivered and collected by their parents daily and they never went to events with Butch alone. His language was foul and crass but that was his demeanor AND reputation.
He was the best coach I have had ever hands down and showed us what needed to be done to succeed and most importantly how to train properly. He took mediocre state girls 14 players and turned them into WTA players by the age of 17. Nearly every young female he worked with played on tour for some time. So, somewhat a legend in his own mind, however, did produce some extaordinary talent. When I heard about this, I just had to provide these tidbits.