One reason why I do not always give my references ahead of time for job interviews (unless asked) is because on 2 separate occasions that I know of, employers have phoned up a reference before even meeting me to ask if I had a disability. These employers believed I did as my application had stated that I had worked and volunteered at some disability organisations.
When my reference said I did, the employers said they were not interested in interviewing me then even though I was fully qualified and my disability did not affect my ability to do the job. Interestingly enough, both employers were suppose to be practicing equal opportunity. One was even promoting the hiring of people with disabilities, and the other had received a subsidy to go towards hiring an employment disadvantaged person for the position that I had applied to.