My reaction, in keeping with my investigative mind, was to offer that it would be a damn fine thing if it were true. Think about it: if businesses actually DID pay women some reduced amount compared to their male counterparts, then it would stand to reason that those businesses would JUMP on this. Why hire men at all when they can realise immense savings just by hiring women with the same skills as men? Think of the possibility of business expansion!
All sarcasm aside, the notion of a 'male dollar' is specious on the face of it. No business can or does last long by hiring purely on the basis of the sex of the employee. The purpose of any rational business venture is to attract the best talent and pay market wages. Why? Or, why NOT hire women at lower wages BECAUSE they're women? The answer is: because under capitalism or even semi-capitalism as we have today, any business that pays some group less because they belong to that group will soon find they are bleeding talent to their competitors.
I work in the enterprise software field. Every day there are market pressures to continually improve the products and lower the costs of development. If my firm were to make its hiring decisions on the basis of sex alone, it would soon find its competitors overtaking it. It would then face the threat of sure failure if it continued in its irrational hiring practises or change its ways and hire on the basis of talent alone.
Another common claim is that between two equally qualified candidates, it is usually the man who is hired over the woman. This simply cannot be true, either. The stakes are too high for an employer to make the wrong hiring decisions. They MUST hire the most qualified or suffer the consequences quickly. In reality, there is no such thing as two equally qualified candidates for a given position. The education, aptitude, drive and prior work experience will always favour one candidate over another, regardless of sex. The two finalists vying for the same job may be close competitors, but one will always be the better choice.
In the end, one must constantly challenge oft repeated bromides. Just because one makes the same claim over and over again for decades doesn't make it true. To arrive at the truth, one must remain ruthlessly logical and look for the evidence, just as crime scene investigators must sift through mountains of facts to catch a criminal.