I never ever hated her nor dislike her. I wasn't a stan during TF era but I guess I would be pissed about some outfits like kermit dress. She is much more fashionable now.
I hated Nicki for 28 hours - from the time she did the Grammy's performance until the time Starships was released. I really really didn't like the Grammy's performance... But luckily Starships rekindled my love for her.
Also, I used to love Rihanna. When she dropped Russian Roulette, I was NOT impressed. Then when Rated R leaked, I dropped her completely. So I guess I've hated Rihanna since November 2009.