Just because you belong to some professional organization does not qualify you in the profession. However, membership in PPA shows the photographer is committed to the profession. Annual PPA dues are close to $300, so you can be assured fly-by-night wedding photographers and those in it just to make a buck from you will most likely not be members.
Of course, I am a member of PPA. Additionally, I enroll in PPA professional photographer developement classes to increase my skill level. Also, I am a member of Wedding and Portrait Photographers International (WPPI), another well known photographer organization.