ZACH: This place stunk. It’s Bush League.
Bush League is American slang for something which is of an inferior standard; unsophisticated, unprofessional, mediocre.
The slang comes from baseball, where the small-town teams below the minor league became informally known as the “bush league”, because of their rural origins, and because they often played on rough fields bordered by bushes. The slang dates to the very early twentieth century.
Note that the role of the repellent Zach is portrayed by Seth MacFarlane, who Daniel Palladino (the writer of this episode) worked with on his animated television sitcom, Family Guy.