Every time, mate!
At least three reasons why you should never "bump" bog windows . . .
1) Even if it's smoked glass, bird stuff will still be seen from inside!
2) Most bogs have the window behind the WC, and what else is there to do when the man of the house is standing having a pee? Look at the windows and study the bird stuff, runs from the top, and lines down the sides which have been there for the past two cleans, of course!
3) A neighbour sees you and your ladder going right past the bog window and spreads the word that you're not doing the full job!
Of course, none of this counts if you give a refund for the missed window