I am a strength and conditioning coach. I have only a few athletes and spend a lot of time with them.
I pass on this advice. For an athlete, look at qualifications but also look at results. The trainer getting significant results with minimal injury is the one you want.
Advice for trainers: ask other trainers for input and tell an athlete when you don't know. There is always someone better than you and your client will respect it. They won't leave you because you don't know something. They will leave you for lack of results and for you spouting bullcrap.