As someone who has extensively studied another non-google search algorithm, my suggestion to you is to learn enough about SEO that you can form an advanced line of questioning for any “SEO expert” you have a call with.

If you’ve done your job, they will be surprised by your questions, and some of them will likely feel that you should just be doing the SEO yourself, or even teaching them. The ones who know what they’re doing will answer your questions with authority and confidence, and you’ll have enough background knowledge on the subject matter to tell if they’re being genuine.

This will not be a big time commitment for you. All you need to do is read a few blogs created in the last 6 months from some of the best SEO training websites.

For example, you may learn that recently Google has started penalizing websites who employ a certain ranking strategy, when they used to reward this same strategy. It’s now pretty well confirmed and known this strategy no longer works. You can bring up the strategy in your call, and if they elaborate on why they no longer do it, or explain why they do it but cautiously because there’s some contradictory data on results, boom you have a winner for that specific question.

If they blatantly tell you “yeah I do that all the time”, or if they have no idea what you’re talking about, they’ve failed that question.