The Watergate affair

Right, let me run this past you and see if you spot anything odd. The roofers' estimate said they would thoroughly check over the entire roof. They came back this morning and said that the water was coming in because there was a big hole in a "watergate" in the angle of the roof (I thought they were called gulleys, but that shows how much I know) and that it was obvious really - you couldn't miss it.

So why did they miss it?

What else have they missed?

Apres moi le deluge!