This one is less controversial, and more just general interest.
If you were dating somebody and your parents and/or siblings absolutely loathed them, would that affect your own view of them?
I'll give two points. One is my opinion, the second is a story.
Firstly, I'd honestly take their opinion and feedback on-board and listen to what they have to say. Maybe they see something I don't? If I hear it from more than one person, I'd seriously think about it as I know then it's not just one person, it's several. That being said, in the end, it's still my decision. My dad has always said, he'll be brutally honest when I meet a girl and if he doesn't like her, he'll say it. But he gave me credit saying I should have no issue given he trusts me to have good judgement and date the right girls (note: hot).
Here's a story. When my parents first started dating, no one on my dads side (Family/friends) liked her. No matter what they said, my dad wouldn't listen and he ended up marrying her. Several years down the track, he finally figured out what they meant when the whole "love phase" started to fade away and he saw her true colours. I'm not dissing out my mum, but she's definitely no saint.
Looking back at it now, my dad certainly learnt and said he will listen to people next time, but in no way regrets it as he got me and my brother out of it.