This time around, it seems that it isn't about the sex but the potential conflict of interest. Perhaps candidates should fill out forms declaring who they have had carnal relations with.
Or, better yet, we should just see if McCain supports any policies that heavily favor the telecom industry. I don't care who he sleeps with as much as I care what positions he favors. (Ok that was a bad pun, but I couldn't resist. Enjoy the mental picture.) We should weigh whether or not his ideas are good for the country as a whole.
In the case of Bill Clinton's affair, he had sex with a subordinate. Presidents should never sleep with anyone who works for the executive branch.