Honestly I think its more about mind over matter kind of thing. People tend to think that they're sick so eventually they do. Whats good about placebo is that it give the patient a positive attitude about their "illness" without the bad side effects.
The interesting thing about placebos is that they indeed do have side effects. Look at any placebo controlled drug study and there will always be a fairly high rate of side effects with the sugar pill. Our minds are really not understood.
Interesting points, but I somehow doubt the cartoonist is a medical professional. Just a hunch.Adam