For the most part, yes. I trust my doctor, so I trust what he tells me. That doesn't mean a person shouldn't question information or get a second opinion; doctors aren't perfect.
Very true. I had one that didn't believe me that a certain medicine was making my heart race and my chest hurt. He told me that wasn't possible. It started happening after I started taking it and stopped when I stopped taking it. He got mad because I told him I wasn't going to take it any more. I stopped going to him after that.