V-necks are simply meant for women. They draw the eye down towards cleavage. That's the whole point (well, that and the neckline is just flattering in general). Men should not have cleavage. Though I'm aware that some men do, that doesn't make it okay to throw on a v-neck and call it a day.
The absolute worst is when muscular guys think they can pull off this "cutting edge" look. Since v-necks are usually tight-fitted, men in good shape who don one are usually looked at as being gay. Now don't get me wrong. I love love love gay guys. But if you aren't gay, then perhaps this isn't exactly a look you should go for.
Also--guy in the picture? Just because you have a tattoo doesn't mean you can wear a bright teal v-neck tee. Just sayin'.
SNL even made fun of the v-neck phenomenon. Check out the vid below: