I almost always do, and don't like people who pacify. If you don't want to hear what someone has to say, tell them so. You don't have to yell at them, but telling them that you're not in the mood to hear what they have to say in a nice way works.
What about you, and do you like people to pacify and pretend they're listening to you, or do you like it when they tell you they can't talk right now? I dunno how the rest of the world reacts to this kind of stuff, but I despise it tremendously.
I'm curious to see what your answers will be.