They really do have terrible personalities and social skills. Normal, healthy adults know that for every action, there is a consequence, and sometimes that consequence is negative. Normal adults take responsibility for their choices, and accept the consequences of those choices. Fats and people with personality disorders think they can do whatever they want because they think there aren't any consequences, or those consequences don't apply to them. When people like this are faced with a negative consequence as a direct result of their actions, they try to deny those actions occurred, or they try to put the blame on someone or something else. (Note: not saying that being fat is a personality disorder, just saying that in my experience, both groups of people who fall into those 2 categories act in a very similar and predictable manner.)