I would say that it depends a lot of the attention and credibility which dermatologists accord to us.
As an example, one of those I consulted refused to hear that his cream which prescribed to me was totally useless and didn't solve the problem at all.
Finally, he prescribed me again the same cream and gave me name and adress of a psychiatrist because he was thinking that I had a psychological problem about it.
Though, this dermatologist was 'reputable'. In brief, I've learned that all that specialists are, foremost, just mens (or womens) with their own state of mind and attention about theirs patients.