Is there such a thing as being a sex addict?

I know there are organizations out there that are similar to alcoholics anonymous but are designed to treat those who believe they have an unhealthy relationship with sex. I have read their “self diagnosis” questions but I am still not convinced that answering those questions can really diagnose. They are somewhat vague. What is an unhealthy relationship with sex? Since it is a primal instinct, how do you know if it is really unhealthy? Generally sex is considered a healthy, normal activity. I am a bit unclear, so I figured I would as all you smart minds on fluther what you truly believe on this topic.