Happened too many times
Last weekend, I had a photo shoot for 5 models. All were very excited and even email me two days before the photo shoot. 24 hour before the shoot, I emailed them again stating that the makeup artist is charging by the hour, so if anyone could not make to the shoot, let me know ASAP.
Immediately, one emailed back saying that she just realized that she had to go to a friend's wedding (this one had previous 3 no-show record), so I assume the friend got pregnant and had to get married real quick. Another one emailed saying that she had to move to a new house, so I assume that this was not pre-planned, a new house just became available on the market, and was a good deal to grab. The third one, after getting the makeup artist. bought some new outfits for the shoot, had to ride the bus home in the last minute, and I assume that she was home sick after staying in Atlanta for 2 weeks.
Only the paid one showed up with her makeup artist, and we had a GREAT photo session, shooting about 350 images.
From now on, I would request that models pay a $50 deposit (refundable only when showing up).
Some models feel that since they don't have to pay for the shoot, they have no obligation to show up, and there are always plenty of GWC (guys with cameras) willing to shoot them, just for the thrill of shooting a female model for for FREE.