God I hate the oatmeal (the maker of this comic). he might be right in this instance,but his stuff is 9 times out of 10 trash.
Although formulated in a rather negative way, I do think this brings up a valid point.
It's often very difficult to distinguish between the messenger and the message. When you know that the messenger has certain tendencies or leaning, it's difficult not to view the message in that light.
In politics: nobody will take Trump seriously if he would suddenly say: "Immigrants are amazing, we should welcome them with open arms" and neither would anyone believe Elizabeth Warren if she were to say: "I think the rich should pay less taxes and we can easily save that money by putting a stop on abortion funding."
Nevertheless, people from opposing ideologies may sometimes have ideas that are perfectly acceptable even for their biggest criticasters. But the messenger itself may already cause a backfire effect and the idea that an opponent might have something useful to say may by itself already be cause for cognitive dissonance.
EDIT: fixed some minor spelling and grammar mistakes.
Edited 5/10/2017 12:27:58