... don't even know why they are/aren't sometimes.
We just discussed "sexual availability" in a recent post, "She's Probably Already Fucked a Guy Uglier than You," to explain why a seemingly less attractive guy can sleep with a girl that a more attractive guy didn't score with.
In both cases, it's important to remember- both guys met or exceeded the 'looks threshold'.
One night/period of time the girl was available, the other time she wasn't. The guy that Gets Laid is the guy who is in the right place at the right time.
Hot blonde California girls with skin slightly more tan than their pussy hair know him as, "Mr. Right Now."