Final answer:
Allen Ginsberg's poetry often expresses disillusionment with 1950s America's materialism, embracing a raw and spontaneous style akin to jazz music as part of the Beat Generation's countercultural perspective.
Step-by-step explanation:
The feeling Allen Ginsberg conveys through his use of style, structure, and language in his poetry, particularly in A Supermarket in California, is a profound sense of disillusionment with the materialistic culture of post-World War II America. Ginsberg, as a leading voice of the Beat Generation, exemplifies this through a style characterized by spontaneous prose and free verse, which reflects the chaotic and raw emotion of those feeling disconnected from the burgeoning American dream of prosperity through suburban life, technological advancement, and consumerism. The counterculture represented by Ginsberg's works stands in stark contrast to the period's prevalent ideology of conformity, embracing the beauty and spirituality found in non-materialistic facets of life and the embrace of marginalized individuals and experiences.