Some medical professionals also spread incorrect information regarding medical information. For example, an RN gave us incorrect info regarding something she claimed was necessary and was CDC-recommended. We asked for more information, and lo and behold, the CDC specifically said it was not necessary (and there were no other sources recommending it).

Doctors and their staff have an incentive to perform more procedures/tests because they get paid to do so. Because the patient often does not bear the full cost of procedures/testing, patients often do not do much diligence to see whether these are actually appropriate. While I don't think that the RN we were talking with was being malicious (surely her individual comp would not have been affected), I do think this is a symptom of a system with a principal-agent problem.

Of course, doctors can be an incredible source of information. But with all things, consider any potential conflicts of interest when taking advice.