My experience here closely matches Scott's. I have done a number of trade sessions, with more than my fair share of flakes. I normally use the images for stock purposes, and I use the Getty standard model release, which you can see
here. I have also an FAQ so that models know how it works. And before I shoot I explain to the model that the images will be made commercially available and we don't necessarily know for what purposes. This is really important because you don't want to surprise the model if they find their pictures on a brochure or something later.
I give the model a separate document stating the rights that the have with the license they get. I never give them unretouched images, and the number of images I provide is small, between 1 and 5 from a session.