* AcceptableTargets: A little person is mocked and threatened in ''At The Circus''. It works because it makes Groucho seem [[UnsympatheticComedyProtagonist cowardly and weak]] instead of cruel.
** Upper class people don't generally come up with the longer end of the stick either. But then again, few people get treated well by the characters the Marxes play.
*** Of course, a lot of that comes from the Depression Era roots of the act; Film/TheThreeStooges and other comedy troupes of the time did the same.
** [[BaseBreaker One of the the most hotly debated topics]] among fans is whether or not he sang in the "Sweet Adaline" bit at the opening of ''Monkey Business.''
* DesignatedProtagonistSyndrome: You'd be surprised how many of their movies had ''Zeppo'' in the lead role. Despite being a talented actor and comedian in his own right, Zeppo was invariably overshadowed by his [[LargeHam much hammier]] brothers.
* FandomRivalry: Often with the fans of Film/TheThreeStooges.
* OnceAcceptableTargets: "Then the Headstrongs married the Armstrongs, and that's how Darkies were born" -- Groucho in ''DuckSoup''. Also, Chico's portrayal of an Italian immigrant, Harpo's original "Irish bruiser" character from his vaudeville days, etc. Hey, it was the '30s!
** The "that's how Darkies were born" thing was actually a pop-culture reference: it was a play on an incredibly racist song that was popular at the time, "That's Why Darkies Were Born": the lyrics of which basically said "''someone'' had to be slaves and have crappy lives -- so it's ''you''" It could be read that Groucho-- himself a Jew, and probably quite familiar with racism-- was ridiculing the warped logic of the song.
** Of course then there's the scene in ''The Big Store'' where they have black actors literally picking their cotton in-store...