In Aikido there is no need for yelling... this isnt the military where they are trying to break everyone down and rebuild them in Uncle Sams image.
If someone is actually paying money, I doubt they want to be yelled at - though some people may enjoy the motivation they get from, "come on... one more rep!!!" - which is more of an encouragement yell vs. talking down to.
I do actually know some people who gain motivation from spite. "You think I can't do this? I'll show you!!!" I just personally don't. I prefer the idea of, this teaching style doesn't suit my learning style, as opposed to making blanket statements, "This teacher is bad." or "This teacher is good." Especially since I am not there to make a judgement call.