With all of the exposure this past year we've come to understand that cheating on your wife knows no boundaries...not Democrat or Republican and if, as Pyg says, they're all a bunch of scumbags why should it matter? It matters because it should. That's why most of the peopple who get caught doing it are now out of office.
We have a love affair with those who present themselves as honest, upstanding citizens running as candidates. We want them to be squeaky clean and if we find out anything about them that would alter that impression they're gone and they know it. That's why they try so hard to hide it.
Does it make them any less qualified to do their job? No, it doesn't but I wouldn't trust them again in any area of job or life.