I asked because I have a friend who totally hates my xp. She has never met him, nor spoken to him.
I split from xp almost 4 years ago, and met this friend about 2 years ago, so their paths have never crossed.
Friend asked me about xp a few months after we became friendly, and I explained we had split when DD was 6 months old. She asked why, I briefly explained that I couldn't live with his behaviour, lying, stealing, not holding a job down for long.
Friend asked me what his good points were.
Hmm, cleaning, housework, childcare, made me laugh, enjoyed his company mostly, but that's not enough to make a relationship work if you don't trust the other person.
Since then, friend has brought my xp into virtually every conversation where she talks about her partner, to compare them, obviously unfavourably towards my xp. Even if we are in the company of other friends, she will always compare unfavourably towards my xp, never anyone else's partners/husbands. 
Our other mutual friends are all still together.
She will quite openly say that her partner does nothing around the house, is lazy, mean spirited etc etc but then always goes on to say "but at least he doesn't lie/steal etc like your xp did".
I cannot complain about anyone with the same name as my xp to her, (let's call xp Bob) because she will always always say "Just like Bob the twat then, maybe all Bob's are twats, because your xp Bob is a twat!"
I haven't brought xp up in a conversation for at least a year now, and brush off her questions about when he last saw DD, when he last paid towards DD etc, because she makes these comments, but it's getting worse!!
I wouldn't criticise her waste of space partner, because tbh, it would feel rude to do so, like I am criticising her choice IYSWIM, and since her partner has done nothing to me or my family, I don't harbour any hatred towards him, I feel disappointed that my friend can't see she is worth more, but not hatred.
The other thing which I have repeatedly said is that I am not with xp anymore, so there is no comparison to be made AFAIC. xp is the past.
Yet she still feels so bitter towards my xp.
She has now started saying things in front of DD, like 'I would hate to be related, even distantly to someone called insert xp's surname . I can't think of anything worse!!'
She literally spits the words at you, and DD is listening. 
I replied "Well, DD is related to a insert xp's surname and she seems quite happy. It's not the worst thing in the world you know, to be related to someone you dislike."
She replied "I don't dislike him, I hate his guts, he makes my skin crawl, and I will never understand what you saw in him...EVER!!"
I walked away. 
Ironically, most of our mutual friends claim to dislike/hate her partner, yet they would not say anything to friend, because what is the point?
I don't know, it just feels wrong to me for her to hate my xp so much. I have moved on, and can honestly say I don't think of xp, until he calls me.
I have let it go, so why can't my friend?