I think a sign on the cage is called for and that takes the burden off your shoulders of having to explaine anything to anybody. I find signs get great results (usually).

Some people, no matter what, are going to complain about anything and everything and others, by nature are just plain rude. I asked a co-worker one time "Did you have a nice week end?", and he jumped all over me for asking him about his personal business and how his week end went was NOT my business.. Unfortunally, there are people like that in this world.