Quark had two scenes in DS9 that summed up the Ferengis and Humans perfectly, IMO:
"The Siege of AR-558"
Quark: "You Federation types are all alike: You talk about tolerance and understanding, but you only practice it toward people who remind you of yourselves. Because you disapprove of Ferengi values, you scorn us, distrust us, insult us every chance you get."
Sisko: "Quark, I don't have to stand here and defend myself."
Quark: "Tell me, Commander, would you allow your son to marry a Ferengi female?"
Sisko: "I never thought about it!"
Let me tell you something about Hew-mons, Nephew. They're a wonderful, friendly people, as long as their bellies are full and their holosuites are working. But take away their creature comforts, deprive them of food, sleep, sonic showers, put their lives in jeopardy over an extended period of time and those same friendly, intelligent, wonderful people... will become as nasty and as violent as the most bloodthirsty Klingon. You don't believe me? Look at those faces. Look in their eyes.
I don't think there have ever been better summations of the two species in Trek.
I, too, hated the Ferengi with every fiber of my being when I first saw them, but they definitely evolved into one of the most interesting races shown in the series and the Rules of Acquisition was a brilliant codification of their culture.