I think it's hinted that they are. I don't think they say "humARNS" like that due to a speech defect. I think they say it cos they don't like Xenos like us. They like our latinum.
Also that happened at the very end of ds9, and only when the least ferengi-like ferengi ever became grand nagus, and his advisors were, his non-ferengi wife and his give-no-fucks civil rights leader mother.
That ending is hilarious to me. Societies just don't do a compete 180° over the course of a year or so. Changes at that level are very, very slow. Taking centuries in some cases. But all of a sudden, they have taxes, social programs, environmental programs, etc...
I know Ferengis are portrayed as non-violent, but I would think makes such rapid, unpopular changes would lead to some level of violence/civil uprising.