Sufferers are disgusted by almost everything. They find any contact with dirt, real or perceived, disgusting and as a result their lives are hopelessly constrained. Everything they do, even simple tasks like making a cup of tea, turn into lengthy rituals designed to avoid contamination. But if too much disgust is abnormal, so is too little. As we grow up we are taught that we should be disgusted by certain things.
Society shapes our disgust response.
Babies, for instance, have to be taught not to touch their faeces. Also, different cultural groups teach their children to find certain foods abhorrent. Later in life, our disgust response is seen as a key element in what makes us civilised. People who eat with their mouths open, revealing saliva and half-chewed food, are disgusting. They must be taught to change their behaviour.