This seems like an intentionally inflammatory thread, but to take the question more seriously than it deserves to be, I'd have to say that if a very promiscuous woman enjoys well-endowed men it would make sense considering that she is probably mostly interested in the sexual aspect of new relationships and jumping from one partner to the next in rapid succession means that it's easier to focus on insignificant differences between each of those many partners. If you've only slept with three men, you'll probably judge each of them more on individual skill and personality as these things ultimately make a bigger difference and your range of experience would be so limited that you couldn't really make any meaningful generalizations apart from these more significant factors. If, on the other hand, you have been with 100 or 1000 partners, then you can start to make generalizations. One of those generalizations could be that, out of 50 partners that had small dicks and 50 that had big dicks, even though each group included both poor and talented lovers, you may have tended to enjoy sex with the well-endowed partners more.
Now, when it comes time to apply those generalizations, a very promiscuous woman will be more likely to go for men who have the less meaningful aspects that they are looking for because these women are not interested in investing a lot into a relationship and not afraid of getting stuck with a guy who might be wrong for them in other more important ways.