There's a famous quote by one of the staff of Unseen University, where they say something along the lines of the university being a great place if it wasn't for all the bloody students. Does anyone have the exact quotation?
I have only found two quotes for now (source) :
In Interesting Times
Many things went on at Unseen University and, regrettably, teaching had to be one of them. The faculty had long ago confronted this fact and had perfected various devices for avoiding it. But this was perfectly all right because, to be fair, so had the students.
In Moving Pictures
"Students?" barked the Archchancellor. " Yes, Master. You know? They're the thinner ones with the pale faces? Because we're a university? They come with the whole thing, like rats --"
Edit : More from Hogfather, I think that's the precise formulation you are asking about.
"I could certainly run a marvellous university here if only we didn't have to have all these damn students underfoot all the time."
There is also another University-related joke in the Last Continent referring to the methods by which Unseen University acquired staff:
"You found an empty room, turned up for meals as usual, and generally no one noticed, although if you were unfortunate you might attract students."