Titan & Cuddles - Skeptics can certainly believe in modern medicine, but need still be distrustful of argument from authority even from MDs.
After all, MDs promote quackery too y'know.
http://en.wikipedia.org/wiki/Appeal_to_authority
"There are two basic forms of appeal to authority, based on the authority being trusted. The more relevant the expertise of an authority, the more compelling the argument. Nonetheless, authority is never absolute, so all appeals to authority which assert the authorities' claims are definitely true are fallacious.
The first form of the appeal to authority is when a person presenting a position on a subject mentions some authority who also holds that position, but who is not actually an authority in that area. For instance, the statement "Arthur C. Clarke recently released a report showing it is necessary to floss three times daily" should not convince many people of anything about flossing, as Arthur C. Clarke is not a known expert on dental hygiene. Much advertising relies on this logical fallacy in the form of endorsements and sponsorships.
The second form, citing a person who actually is an authority in the relevant field, carries more weight in that the authority is more likely to be correct. However the possibility of a mistake remains."
Argument to authority is not always a bad thing. It is usually called out as a fallacy when the first form is invoked. This seems to happen with a lot of mindless celebrities using sCAM, and if they do it it must work.
In this case though, only the second form applies. Of course we shouldn't believe everything a doctor says just because they are a doctor. However, any qualified doctor has spent many years learning about medicine and they are likely to know what they are talking about. As I said, if I go to a doctor and they prescribe a drug, I won't argue with them because I know they are likely to know what they are talking about. This isn't argument to authority, it is simply their job. If they are doing it wrong they will be investigated for malpractice and probably lose their job and end up in jail.