Many schools try to abide by the Dec 1 agreement but as my soon-to-be-classmate (Desi) told you at some interviews they will drop hints.......BIG hints.
At everyone of my interviews there was a hint or two dropped. You just have to listen and then weed out what they are saying. At one interview my interviewer said "Well my advice is you live in the Grad housing next year". At another interview as I was leaving I was asked "So will I be seeing you at my place next Thanksgiving?", and at another "I like what I see here, I wont send you home unhappy". You see they let you know, because they know you are applying to several schools and just like you need them, THEY NEED YOU.
Yes, private schools are a little more liberal in dropping hints, but state schools do too........"the sooner you move here, the faster we can help you establish state residency for you".
Apply early, take notes when you interview, spend a couple days looking around and make an informed decision. What was myfirst choice rapidly changed after a few interviews.........now Im going to my first choice. ...........