I usually listen to what doctors have to say, and trust their judgment. Especially since I have next to no formal education in bio or medicine.

I did resort to "self-diagnosis" once, though: for R-CPD (no-burp syndrome). Most doctors simply don't know this condition exists. I brought it up with my GP (whose referral I needed to see a specialist in Ontario), prepared for some pushback, but was pleasantly surprised that he did some brief research and then helped me forward.

Then again, I may have been lucky. I still hear stories of doctors who are less than cooperative when patients bring them "self-diagnoses", even for something as open-and-shut as R-CPD. But if most of those "diagnoses" are BS, then I can empathize with the docs, too.