An ethical dilemma

Here is a scientific ethical dilemma that came up in conversation recently.  What do you do if you get a positive referee report, but it's clear from the comments that the referee completely misunderstood your manuscript, or basically had no clue at all?  Do you point this out to the editors?  I'm actually a bit surprised that this never seems to come up, given how often people complain about the complementary case of a clueless referee that bashes a paper because of a lack of understanding....