it also goes the other way..
It also applies that one should check out the person joining a boat, since when you are at sea anything could happen.
I've had a blog up for the boat for the last 4 years now, and that is fairly easy to check out past history of the boat and it's owner. It's all fairly transparent and I would have more to lose than anyone coming on the boat.
As for preference for females, I just tend to get along with them better.