At American colleges, are student evaluations of teaching subject to code of conduct? It is well-known that student evaluations of teaching tend to be spiced with language that is insulting, sexually harassing, sexist, or racist. 

Most American colleges have a code of conduct that is would disprove such remarks if they were face-to-face or anonymous writings on the wall. 

Does that code of conduct apply to student evaluations of teaching at American colleges, or are they considered exceptions? These course evaluations are largely anonymous, which is why students feel enabled to engage in speech they usually wouldn't utter. But this occurs via university media, not somewhere out in the streets or the dark web.
Yes, they are subject to the code of conduct.  However, they are usually anonymous, so there is no means of enforcement.