They seem nice at first, but...
I recently received an email from a current grad student in the program to which I'll be attending in the fall. She congratulated me and such, then ended the email by offering advice or help with anything I needed, as well as to tell me what the professors are really like. This emphasis of really really made me wonder: are you trying to tell me that you didn't give me a good impression of them when I was on the campus looking at the department?
I feel like this is said a lot around university campuses. It seems to me here that the speaker is letting you know in a nice way that they flout the quality and manner maxims for the sake of being polite in order to ease you into the program/new professors.
I find this to generally come as a surprise when someone says it, and wonder why the reality was not stated in the first place.

Comments
I agree that we flout these maxims all the time. Sometimes I feel it is good to do it, such as using a euphamism to avoid being too blunt. Other times I think it's better to come out and be completely honest, such as when you're describing the professors since they can either make or break a class/department.