How do I explain to some of the women in my local Mothers Against Drunk Driving chapter that they aren't attractive enough to be in a MILF carwash calendar?

Many people aren’t aware of how serious drunk driving is. Many people aren’t even aware that it’s wrong to drink and drive! I would like to raise money for my Mothers Against Drunk Driving chapter by producing a MILF carwash calender. However, some of the women who expressed interest in being photographed for the publication just aren’t that attractive. How do I let them down easy?