How does it make you feel if a friend doesn't agree with you on a third party?

So I have this person that I really can’t stand and today I was talking to a friend whose opinion I really respect on things. And I’m not totally clear on how this friend feels about this person but while we were talking he kept making statements that seem to demonstrate that he was somewhat defending the person. Not necessarily in how he treats me personally but just for his actions in general.

So my question is how does it make you feel when one of your friends at least partially takes the side of somebody that you don’t like? Do you get upset with your friend? Are you able to truly listen to what they’re saying about the person and take it under consideration? Do you totally change your view of that person or do you maybe look at them with a fresh set of eyes?

I don’t even know how to answer this question myself. I’m not really upset with my friend because I appreciate the fact that he is good at seeing all sides of an issue as I usually am. But if I was being totally honest I would say it kind of irked me at the time but it has given me a lot to think about.