Or, as I prefer to call him, The Male Slut.
(Yes, I know this post may be more appropriate for a historical romance blog, but this phenomenon has creeped into contemporaries and even romantic suspense and I feel it needs to be stopped for all our sakes.)
This type of hero abounded in the early romances I read. Old-school historical romances usually opened up with a scene of the hero and one or more women who were definitely not pure enough to be the heroine. Or a duel between the hero and the husband he cuckolded. Some of these heroes also cheated on the heroines mid-way through the book, usually as a way to drive the heroines away because they felt they weren't good enough for them. (Susan Johnson, however, basically stuck with the tenet men cheat when their significant others are not around.)
These heroes were considered virile, manly, et cetera, et cetera because all women wanted them--and had them. They are commitment-phobic because why should they settle for only one woman when they can have them all? Of course, then they would meet the feisty, virginal heroines who would make them change, see the error of their ways, and they would no longer want any other woman but these paragons.
The fantasy of taking a male slut rake and reforming him appears to be shared by many, many women (how else to explain the trope's popularity?)...but I'm not one of them.
Frankly, they skeeved me out. It's not a morality thing for me. Every time I came across one of them, my stomach would shudder as I imagined the possible STDs they would have from sleeping around. And I would always wonder how many bastard children they might've sired and didn't know about. And the whole cheating-for-her-own-good pissed me right off. Made me want to reach into the books and shove the heroes over the nearest cliff, and maybe the heroines with them for forgiving the jackasses.
SNL did a skit back in the 90s about the world's ultimate rake that perfectly portrays my take. If you have a few minutes, Google "SNL James Bond STDs".