In John Updike's short story A&P, the narrator Sammy has been ogling a group of customers at the A&P store:
In walks these three girls in nothing but bathing suits. I'm in the third check-out slot, with my back to the door, so I don't see them until they're over by the bread. The one that caught my eye first was the one in the plaid green two-piece. She was a chunky kid, with a good tan and a sweet broad soft-looking can with those two crescents of white just under it, where the sun never seems to hit, at the top of the backs of her legs. I stood there with my hand on a box of HiHo crackers trying to remember if I rang it up or not.
But when McMahon does the same, Sammy feels sorry:
The girls had reached the meat counter and were asking McMahon something. He pointed, they pointed, and they shuffled out of sight behind a pyramid of Diet Delight peaches. All that was left for us to see was old McMahon patting his mouth and looking after them sizing up their joints. Poor kids, I began to feel sorry for them, they couldn't help it.
Why does Sammy feel sorry after seeing McMahon is making eyes at the girls, while Sammy himself was enjoying making eyes at them?