I've had different experiences. One group in my area starts each meeting by reading a passage (from where I don't know) where it says something like: "Even though we recognize that drugs and gambling can be addictions, Al Anon is for family and friends who are dealing with the effects of alcoholism. Although others are welcome to work our program, only those who are suffering from the effects of alcoholism are able to become members." The statement went on to say something about needing to maintain the integrity of the group as being for those dealing with an alcoholic.
At first I just tried to ignore that and focus on the fact that my RAS is truly an alcoholic as well as being a drug addict... but that exclusion statement every week ended up making it impossible for me to feel comfortable.
I attend a different Al Anon group in my area that is wonderful. It really is important to shop around. Groups have different personalities.