Perhaps as a suggestion Purestorm could give people the option of deleting positive feedbacks that are not longer relevant from their own profiles*, eg from people who are no longer on the site, or perhaps from photographers etc who do a style the model no longer wishes to be associated with (a valid reason- as a model may wish to keep her positive references relevant to her current styles.) IE, people may wish to prune references so as to have several relevant ones from current site members, rather than a larger number from departed members etc.
Occasionally, too, there may be instances where a person no longer wishes to be associated with another member, for a variety of reasons. It doesn't seem unreasonable to allow a person to remove the positive reference if they choose to.
For sure, it might mean people could remove stuff they didn't want others to read, but if it's a positive reference only that they are allowed to delete, that shouldn't be an issue.
*This is about people being able to delete references left for them, not the references they left for others.