Why do you hate Dean / Jo (or just Jo) ?

I don't like Jo much. To me she seemed the same as above ^ a wannabe hunter. In a couple of episodes, she rubbed me the wrong way and I found her annoying at times too.

I am vehemently against Dean/Jo because Dean was never, ever interested in her. He never called her, never talked about her, nothing. And I've always seen their relationship as a brother/sister one. If they had been made a couple I think it would have seemed forced and mostly one-sided on Jo's part.

I've never liked Jo. She just generally annoyed me for some reason. She just seemed like such a wannabe hunter.

Jo/Dean I've never liked because it seemed forced, and personally I perceived the whole Jo/Dean relationship as being more brotherly-sisterly as opposed to anything romantic.

Relationships introduced on SPN have just never appealed to me really, because they all seem forced, and it tends to throw the brother dynamic a bit.

that is news for me i thought ever1 love D/J

Dean and Jo obviously wasn't ment to be. After observation, I noticed Dean treated her more like a little sister rather than someone he wanted to date.
I felt like she was to show-offy to pretend she was a down-to-earth hunter. She was one of those characters that just rubs you the wrong way. I honestly feel like she was just thrown in the story to inspite jealousy in the viewing demograph of "Dean Girls." But Jo's era is over and that's a sigh of relief. But that's my opinion. :)

It's not the fans who hate Dean/Jo (or Jo only)... It's actually the fangirls. Idk but I wanted them to date in some scenes but in some I see the brother-sister type of love between them and it's actually sad to see Jo die... :(
Tbh the writers of the show and the fangirls are to blame for this Jo hate. Fangirls hate literally ALL of the love interests of Sam and Dean and they annoy sometimes. And i'm pissed at the writers for just letting the fangirls get what they want.
I'm sorry if this comment was offensive, I apologize, but this is my opinion.

I like Jo - she and Charlie are tied for my favourite female character. However, I don't like Dean/Jo as a pairing. I've 2 reasons for that.

1. The writing of them as a potential couple seemed to be too inconsistent. Firstly, Dean is hitting on her but doing so halfheartedly because he's grieving. She rejects him because she knows he'd only be interested in a one night stand. Then they seem to develop more of a sibling-like relationship (not helped by Alona Tal being unavailable so often). Then in her final episode, he hits on her again and she rejects him again. I mostly just read that final kiss as Dean giving Jo what she wanted, or what he thought she wanted, because she was dying.

2. I ship Sam/Jo, so I can't really ship Dean/Jo. Also, putting Jo with Dean just seemed a bit too obvious.