This is a method of attacking a person’s character in an argument or after making a statement.
It’s known as a logical fallacy. While logical fallacies are and should be defined in an effort to reduce confusion during arguments, they are often used in an effort to deflect arguments in interviews or conversations that occur on the news or in the political arena. Thinking that politicians are unaware that they’re using these methods as distraction is mistake. They know exactly what they’re doing, as anyone who is in politics is keenly aware of the questions they do and don’t want to answer. It is a deflection, at best, in response to an argument.
It is important to note: Ad Hominem attacks may be a proper method of calling a person’s credibility into account after making a statement. Statements and arguments are different things.