You cannot consciously change what you like or dislike (especially, are disgusted by). This instinct is partially helpful: a bad experience can lead to disgust (possibly through trauma) which will help you avoid it in the future, without having to consciously recall the details of the bad experience.
However, this instinct is also the basis of a tremendous number of ways people can be socially manipulated. It is somewhat surprising that evolution has deemed it to be more good than bad.
What, if anything, should a nanny state do to protect people from being manipulated in ways that humans are biologically programmed to be susceptible to? (Should it limit speech?) If social pressures select for people who are less susceptible to manipulation, this may decrease the effectiveness psychological memory, which may have long-term consequences on human evolution.