Men have the stereotype of being more difficult to photograph than women. While this may often be the case in terms of breaking the ice and getting them to warm up to the camera, there is no limit once you break past the initial unease for finding appropriate posing and bringing forth emotion to create stunning male portraits.
As someone who has spent time in front of the camera, and even more time more behind it, I can attest to the powerful reluctance that many men feel when being photographed. There is an intimacy that takes place when posing for a camera, and most men are naturally uncomfortable with such closeness with a stranger.