Back 20 years ago when my brother was having GI issues no doctor could figure out what was wrong with him in WI. He ended up going to Mayo in MN and they were the only ones who figured out he had UC. I suppose that's why I went there way back then too - from his experience. In fact I am seeing the same doctor now who he worked with back then!
For me I suppose its that I feel I can trust the doctor, even if they don't have any 'magical' answers for me. As long as the listen to me and work with me, ask me how I feel about what they are suggesting rather than just assuming they know it all. If I trust the doctor and feel that their knowledge is based on solid research and experience then I feel better about taking the medications they prescribe me. I feel as though at least I can trust they know the risks and benefits and what is best for me in that situation and they aren't just looking at a list of meds in a book and picking the 'next' one one in the course of treatment. I definitely feel that way now but in the past with other docs have felt the exact opposite!