You know, I actually forced myself to plow through it once. If you recall, Rand had the Dagney Taggart's taxi driver chuckle appreciatively after Galt left the air -- I had to conclude that any author who can make somebody chuckle after that has a rather tenuous grasp of human nature.
I'm a bit of an "armchair philosopher" and I like most of the objectivist philosophy. However, I believe one has have to have an objective moral foundation in order for objectivism to work. We are obviously moral creatures - by that I mean we all know right from wrong. This is an objective truth, but objectivism does a horrible time of showing how to arrive at an "objective morality" from a purely logic based system. In my particualr view this is where God comes in. If there is a God, then there is an objective morality, and this explains why we all seem to know what is right and wrong. From this foundation one does rationally know what is in his/her rational best interests - one can see why it is wrong to iniate force and so forth. From this point objectivism, for the most part works, and works very well IMHO.
I conclude that you have a tenuous grasp human nature. People laugh for many reasons....humor, sadness, shyness, discomfort, pain....