Intent be damned! It really doesn't matter whether someone intends to be rude. It could still miss the mark. All that matters is how the message is received. This is true even if the action or inaction is unintentional. If the other person perceives a slight, then for all practical purposes there is one.

Just as a parallel of sorts, try putting this in the legal context of sexual harassment. The (US) law states that it is deemed to have occurred if the complaintent perceives that it did. Quite a sticky wicket, that.

But getting back to the communication question, the real can of worms is in just how much responsibility you should accept for how another person receives your actions/inactions.