Though not a man, I can certainly speak on this subject.
I spent two and a half very lucrative years as a topless dancer. The clubs I worked most often featured three song “sets” with dancing and stripping through the first two songs, and finally losing the top in the third song, to great whooping, hollering, and applause.
Although there was always applause when the top came off in the third song, you could probably guess the breast size by by the loudness and enthusiasm. If there was enough uproar, the manager might have the girl dance topless to a fourth song. Like an encore at a concert. Song four could bring absolutely incredible tips!
Abandoning any sense of false modesty about my jackpot in the genetic lottery, I was petite, young looking, had a pair of natural 32D breasts. The club owners loved me because of the crowds I could bring in. Club management always wants at least one busty girl in each rotation, because busty girls bring in more drink buying, cover charge paying, dancer tipping customers, which makes for happy owners, bartenders, waitresses, and dancers. With the right amount of tease, the mere possibility of seeing a pair of big ones can turn otherwise normal, intelligent men into panting, drooling idiots.
Of course, the alcohol helps too.
I don’t know if it’s genetics, culture, or social conditioning, but very few men are indifferent to tits. And most like them large. At least up to a point. Personally, I think that Bear Cub's posted photo is just grotesque, and I'd bet that most men would agree.
For the readers out there, here’s a great book on tits, and, in the OP’s words, “men's fascination of women's breasts.” From a large-breasted woman's point of view.
I highly recommend
Stacked: A 32DDD Reports from the Front by Susan Seligson. From Amazon, and the other usual places.
Lindy