Claiming to subscribe to the AAR Canon, regretfully, doesn't have to mean very much. The Canon excludes reading fees and kickbacks for referrals. It doesn't exclude upfront marketing fees or paid editing fees, which are the two most common bad-agent abuses these days. Plus, the agent could be lying. The Canon isn't a regulatory statute--it's a voluntary standard imposed by a professional trade group upon its members. Outside that group, adherence or non-adherence means very little.
To become an AAR member, an agent must have worked as an agent for at least the past two years, and have made a minimum of 10 commercial sales during the past 18 months. The fact that members have to prove at least some level of competence before they can join is the main reason to give AAR agents priority on your query list (in the UK, the AAA serves a similar function, as does the ALAA in Australia). However, as Jim pointed out, some successful agents choose not to join, and some very competent agents haven't been in business long enough to qualify. As always, the bottom line is track record and experience.
- Victoria