Here's a concrete example.
Many people hold the highest moral good to be the elimination of suffering. They believe that we should work to improve the material conditions of the world's least-well-off humans.
Ayn believes these people are evil. However, talking to them, I do not believe these people are evil. I believe they are good people.
Their instincts are human. It is human nature to be made sad by the suffering of others.
Alleviating the suffering of others is one of many things that human value. However, holding this as your highest moral value can lead you to do things that others dislike. For example, you may be motivated to pass laws that take the property from one person and give it to another that needs it more.
Now, humans ALSO value property rights, and some notion of property rights seems just to most people. I am sure you place some value on property rights.
These two instincts drive people to take actions that contradict each other. It is the nature of humanity.
Now, the true believer will insist that there is one right answer and no real contradiction, but their arguments get flimsy and tired after awhile.
I was never "dissuaded" from Objectivism. Rather, I grew away from it over time. I guess I got tired of looking up the answers to tough questions in a book, instead of puzzling them out for myself. Also, the logic just gets thin and unconvincing over time, as when Ayn tries to prove that one moral axiom is better than another. You can't do it. They are axioms. You can't say that a person is wrong for feeling sad at other people's misfortunes (well, Ayn can). It is just a fact.