In order to understand the issue of sexism in John Updike's "A&P" you must look deeper into Sammy's descriptions of the female characters as well as the actions of every other male character. Sammy objectifies and sexualizes the three teenage girls, refers to an elderly female customer as a "witch" after she catches him scanning in a box of crackers a second time, and describes other female shoppers in derogatory ways. Likewise, the other male characters also engage in sexist behavior.

As the girls come into the store, they garner the attention of Sammy and the other men. He goes about his duties, but his eyes and his thoughts are on the girls. He characterizes each of them based on their looks, assigning the name "Queenie" to the most attractive girl. The sexist notion here is that in order to be successful and in charge, a female must be attractive. The elderly female customer becomes understandably irritated that Sammy charges her for the same item twice, yet instead of owning his mistake he ponders that "if she'd been born at the right time they would have burned her over in Salem." The sexist notion here is that it is wrong for a female to point out a male's mistake. Elsewhere throughout the story, Sammy continues his derogatory view of women. He refers to the female shoppers as "house-slaves in pin curlers," as well as other women in his town as "women with six children and varicose veins mapping their legs and nobody, including them, could care less." Sammy clearly has very little regard for women unless they are attractive. In fact, the one thing he does in the story that could be construed as positively standing up to sexism is actually his own vain attempt to impress the girls. After his manager chastises them, he openly quits, hoping his words will be heard by the three girls. He does not do this for their benefit, nor does he truly do it because of the behavior they faced at the hands of his boss - he does it for his own personal gain.

However, the issue of sexism goes beyond Sammy's descriptions. Lengel, the manager of the store, chastises the three girls for what they are wearing. "Girls, this isn't the beach," he says. "We want you decently dressed when you come in here . . . After this come in here with your shoulders covered." The sexist notion here is that if women want to be part of society, they must adhere to male views of decency. When Sammy catches another male employee looking at the three girls— something he has been doing himself—he hypocritically feels sorry for the girls:

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.

The sexist notion here is that the three girls are powerless at the hands of the male employees—they "can't help it" that they are attracting the attention of the men. Even his friend, Stokesie—married with two kids—appears to make fun of the girls. All in all, there isn't a single male character in the story that does not approach, think about, or interact with the three girls in a sexist manner. While the reader learns that Sammy is immature, sexist, and in many ways a terrible person, having these other male characters with negative views of females only adds to the overall sexist atmosphere of the story.

From a feminist stand point, the young girls in A&P are objectified by the men in the store.   The narrator looks at them as in need of protection.  He bases this opinion on what they wear rather than who they are.  The story is told through a limited point of view, so the reader is not aware of the thoughts and beliefs of the young girls.  The reader can only see and hear what they say, thus relying on the unreliable point of view of the narrator. 

This story can be viewed as sexist as a result of the narrator's descriptions.  The narrator is a teenage boy who filters everything through the mind of a teenage boy.  The three girls that he sees are objects which he describes openly and honestly as he views them.  His description focuses much on their bodies and is rarely flattering.  In addition, the other women shoppers in the store he describes in very negative terms calling one a witch and comparing some to animals.

Why do some readers find "A&P" offensive and sexist?

Some readers might find “A&P” to be offensive and sexist because the narrator, Sammy, objectifies the girls who come into the store. Recall how he talks about them at the beginning of the story. He describes them as if they are physical objects:

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 back of her legs.

Sammy’s focus on the girls’ bodies makes it seem as if their physical appearance is the most important thing about them. In his mind, he calls the girl he finds most attractive “Queenie” because he assumes that she is in charge of the other girls. This assumption suggests the false, sexist idea that girls must be physically attractive to men in order to have power.

Readers also might find the way Sammy’s boss Lengel treats the girls as sexist. He gets mad at the girls for wearing bathing suits in the store and tells them:

Girls, this isn't the beach. ... We want you decently dressed when you come in here. ... After this come in here with your shoulders covered.

Lengel is essentially saying that the girls must adhere to a male definition of decency in order to be accepted in the store. Readers never get to hear the girls’ point of view, and the girls serve merely as an object to showcase Sammy’s limited perspective on the world.

It is worth noting however that his story is an examination of a heterosexual nineteen-year-old boy’s youthful naivety. In exploring the disillusionment of young adulthood, Updike worked to portray the ideas of people this age as accurately as possible. An essay that argues that this story is not sexist would likely focus on why Updike included chauvinistic commentary.