Also, I read the reason why.
The reason you gave is a different kind of ad hominem argument, known as Tu Quoque.
Even if Sarah is out and out hypocritical, that doesn’t mean that her arguments are invalid.
Once again, it’s attacking the messenger instead of the message.
If her argument is "don't vote for Ted, vote for Don because Ted flip flopped", there are two reasons to dismiss that argument.
1.) Trump flipped as recently as July 2015.
2.)Because one flips on the issue, such as Trump in 2015, such as Palin previously, and (supposedly for the sake of argument)such as Cruz in 2013, doesn't mean that one isn't correct on the issue today.
Once again, it’s attacking the messenger instead of the message.
No. Again it's relevant. It makes the point. See my argument #2.
I'll give you another example.
Let's say that an alcoholic 10 years on the wagon, walks into a job interview. The job interviewer, who also is an alcoholic who is also 10 years on the wagon, tells the person being interviewed that he would not hire him for the job because of his problem.
The interviewee then points out to the interviewer, that the interviewer has the same problem and that he still does his job well.
In this example the interviewer isn't attacking the interviewer. He is making a relevant point.
Do I make the point clear??