Ed is absolutely right - a model release is most definitely a contract! It is a written agreement that in exchange for consideration (prints, money, a cup of coffee), the model agrees to being photographed, and that the photographer agrees to the limits of usage defined in the release.
And he and others are also absolutely correct that the standard language of this standard release is totally one-sided in favor of the photographer. But it is a simple matter to change the wording to reflect the concerns of the model. And that is what should be done.
Bottom line is that if the model has special concerns, they need to be addressed and the model release should reflect the agreement between the model and photographer that takes those special concerns into consideration.
And someone also noted that, in Jeanette's instance, one possible solution would be for the model to simply not sign the release. The photographs could still be made, and could be used for club and artistic display, but could not be used for any form of commercial advertising. And perhaps that would resolve the model's concerns. But I feel that because the model has special concerns it would be preferable to execute a release that clearly establishes limits relative to those concerns rather than relying on the assumption that everyone understands and agrees to unstated limits.
I was in a workshop several years ago in which one of the (nude) models worked as a teacher in a public school and was concerned about being recognized. All that it took was to write into the model release that pictures of the model that depicted the model's face could not be used in any way. Problem solved - everyone happy.