Evaluating expertise is hard. And we're not going to show you how to do that in any detailed way.
But we will show you how to sanity-check expertise, to see if they are known to have expertise in their area or more pseudo than science, more salesperson than professional.
https://www.youtube.com/watch?v=yU9JELSQGfU
The first example uses our "Just add Wikipedia" trick. In the second example we show we used: