"[S]tudent evaluations (against which I have inveighed since I first saw them in the ’60s) are all wrong as a way of assessing teaching performance."

Stanley Fish writes:

[T]hey measure present satisfaction in relation to a set of expectations that may have little to do with the deep efficacy of learning. Students tend to like everything neatly laid out; they want to know exactly where they are; they don’t welcome the introduction of multiple perspectives, especially when no master perspective reconciles them; they want the answers.

But sometimes (although not always) effective teaching involves the deliberate inducing of confusion, the withholding of clarity, the refusal to provide answers; sometimes a class or an entire semester is spent being taken down various garden paths leading to dead ends that require inquiry to begin all over again, with the same discombobulating result; sometimes your expectations have been systematically disappointed. And sometimes that disappointment, while extremely annoying at the moment, is the sign that you’ve just been the beneficiary of a great course, although you may not realize it for decades. 

That's not just an old professor complaining that the students don't like his style. Fish is critiquing a proposal — from the Texas Public Policy Foundation, "a conservative think tank dedicated to private property rights and limited government" —  that would give cash bonuses to teachers (at the college and university level) based on so-called "customer satisfaction":

If there ever was a recipe for non-risk-taking, entirely formulaic, dumbed-down teaching, this is it....

ADDED: Normblog thinks Fish exaggerates:

[T]here are some things that even a student can tell. She may not yet know enough to understand all the subtleties of a challenging teaching method, but she does know something, and she knows more as she goes along. She can tell the difference between clarity and obscurity, between a love of the subject from her teachers and a dullness about it, between an enthusiasm for learning and an indifference towards the process and the students themselves, between a conscientious teacher and a lead-swinger, between an inspiring lecturer and a useless one.