By definition, "the best" are a minority of any group
Barring grade or ratings inflation, only a small percentage of any group can be considered "the best." While "the best" agents look out for their clients, they are only a minority of agents at large. Do the "pretty good" and "merely average" agents also look out for their clients? I wouldn't bet the ranch on it.
People have to learn to "follow the money" and to be skeptical of financial advice given by people who are paid on commission. People have to always be sensitive to an agent's possible conflict of interest because it can work against them.