The music on Heavy Petting Zoo has been complimented as "melodic", and the album has been favorably compared to the band's 1991 Ribbed LP, but although tracks like "Hobophobic (Scared of Bums)" and "Freedom Lika Shopping Cart" have been lauded for their witty titles, they have also been criticized for being overly cynical.
The track "August 8th" makes reference to the death of Jerry Garcia. Songwriter Fat Mike commented that he wrote the song, "cuz I fucking hate the Grateful Dead, but it turns out I had the date wrong. He really dies on August 9th. Whoops. I guess I'm lame." According to Fat Mike, the first half of "The Black And White" is concerned with a repressed homosexual male living in "Small Town, USA".