A recent article in one of our medical newspapers reported that when surveyed, patients still prefer for his/her doctor to appear professionally dressed, including wearing a white lab coat.
I suspect those surveyed may have had other opinions if given additional data.
Many studies over the years have shown that medical personnel change their lab coats very infrequently. In one study, over 50% reported less than once a week. Other studies have shown that many antibiotic resistant bacteria, such as C. Difficile and MRSA, can thrive on a lab coat for a month or two if the coat is not properly cleaned.
I stopped wearing a lab coat years ago for this very reason.
I ALWAYS think of this whenever I see my colleagues who still do.