Yes, "I'm too busy" is usually code for "Your request is not important enough to me to bump the other things that I want to do off of my todo list." So what?

Yes, "I'm too busy" is usually code for "Your request is not important enough to me to bump the other things that I want to do off of my todo list." So what? People can plead, barter, and argue with you if you say that something is not important to you, but "I'm too busy" is pretty unassailable. What, exactly, is so much better about giving a flat "no" - honesty? Please...you're still arbitrarily shutting down the request without giving a reason, and "not important enough to me" is as implicit in "no" as it is in "too busy". To me, "busy" means that I have at least a hundred and fifty years worth of things that I'd like to do, and sixty years to get as far as I can with it. If you want to push your way in there, give me a damn good reason, and if you haven't, I have no problem saying whatever it will take to make you go away with as little interruption to my life as possible...