Ah yes, skylights..... I've paid out a few bucks on them before. The real stinger is that you can't always see an improper install in a visual inspection.

I actually had one in my own house about a year after I had the roof replaced. After it was torn apart you could see that the upper 'L' flashing was snipped a bit too far at the crease and it led to a leak. I was surprised how small of an imperfection led to a leak.

And I know.... I probably didn't have to pay for the one I did but sometimes it's just easier.

As for the one in the picture, I don't see the problem either.