I could tell she was a real hikester because when we all stopped for a break at the top of the ridge, she drank kombucha from an old jam jar and munched on brown rice sushi.
Like a hipster, except a hatester "hated" something before it was popular to hate that particular product or service. A hatester refuses to see any value in a product or service that has good qualities because of real or perceived flaws which are typically minor in overall scope.
"As a hatester, I hate Mass Effect 2 since its story is non-existent except for the parts that flesh out the characters and the universe in a way that enriches the experience of the franchise. It's now popular to hate on Bioware, so I'm going to say that Mass Effect 2 isn't worth playing at all despite its universal praise when the game came out and its numerous Game of the Year awards by respectable outlets such as Giant Bomb."
The word hatester is often used as a pejorative to describe someone who is pretentious or overly trendy, and cannot be happy for those who don't agree with them.