Question refers to A&P by John Updike. Thank-you for your opinions, they all count!
Consideration of the setting of this story is integral to reader judgment. For, in the late fifties, for girls to wear bikinis was rather risque behavior (Remember the song "Itsy Bitsy Yellow Polka Dot Bikini" and the girl was afraid to come out of the water?). For them to walk into a store with nothing over them is certainly out of the norm for the setting. Queenie attempts rebellion with her straps "pushed off" with "nothing between the top of the suit and the top of her head except just her..." Few girls of Updike's story's era would attempt to enter a store in such a manner without being brazen and immodest.
I lay most of the blame on the girls. Think of all the body parts that they didn't have to show if they didn't want men to look at them:
a) "those two crescents of white just under it [her buttocks], where the sun never seems to hit, at the top of the backs of her legs";
b) "her belly [which] was still pretty pale;
c) "these long white prima donna legs";
d) "They [the straps of her bikini top] were off her shoulders looped loose around the cool tops of her arms, and I guess as a result the suit had slipped a little on her, so all around the top of the cloth there was this shining rim";
e) "this clean bare plane of the top of her chest down from the shoulder bones like a dented sheet of metal tilted in the light."
Yes (as my friend pohnpei points out) the narrator objectivizes the girls as soon as he sees them. But what was the poor fellow supposed to do? He's male, you know. And these girls--don't they own a tee-shirt to throw over themselves when they leave the swimming pool?
You can definitely argue this both ways. I'll go with the idea that it's the men's fault.
My main evidence is the way that Sammy reacts right from the start. The first thing we see in the story is him describing the body of one of the girls, starting with her "can." So what we see is that Sammy sees this girl only in terms of her physical attributes and mostly those attributes of hers that are connected to sexual attractiveness. (He doesn't talk about her hair or how tall she is or anything -- just about her body shape and what her butt looks like.
Now, I'm not sure that we should blame this on Sammy or on men in general -- maybe it's not their fault. You could argue that it's really the fault of society in general that socializes them to think that a woman should be looked at in terms of her attractiveness as a sex object.