A method and apparatus to help detect that a particular location determination process is unreliable and to help exclude location fixes established with that location determination process from being used as a basis to provide a location-based service. In accordance with the disclosure, a server may receive at least three location fixes for a mobile station, all corresponding with each other in time and each established with a different location determination process, and the server may determine that one of the location fixes is relatively far away from the other location fixes and therefore that the location determination process used to establish that location fix is unreliable. In response to determining that the location determination process is unreliable, the server or another entity may then exclude location fixes established with that location determination process from being used as a basis to provide a location-based service.