Proof
Of course people will never accept proof when it disagrees with what they want to be true.
I am disputing that these promiscious men are "heterosexual" I dispute the terms heterosexual and homosexual as being spurious, but that is another matter.
A number of experiments have been carried out - reported in Scientific American in the 1980s which proved that promiscous men tested according to the iris dilation test exactly the same way as did acknowledged Gay men - proving that womanisers were really Gays in denial! I have in my own experience noted that womanisrs were inclined to be happy only when they were intimate with men. They do not really like woman, but they abhore anyone thinking they are homosexuals so they pretend.