Wow, I really disagree with that statement. The whole reason I love slasher movies is because the people getting killed are either idiots or jerks. So when they get killed, you don't feel bad because it's their own damn fault for being so stupid or they're receiving what they deserved. The best horror movies are the ones where the bad guy wins in the end, anyway.
It works the same similar with Drag Me to Hell. She seems all sweet at first, but when she starts going through the ordeal, you start to see what sort of person she is. Like laughing and calling the old lady a bitch after locking her out of the car. That's just BEGGING for comeuppance. Then you have the idiot boyfriend who thinks she's going crazy.
I'm actually in the middle of watching Drag Me to Hell right now. I'm reminded heavily of Tales from the Crypt. It's purposely campy and over the top, with a lot of moments that could be scary or hilarious. And I really disagree on its jump scares. It's not just the jump scares it does, but the build up to those jump scares. Even when you know, you know, you totally know that a scare is coming, it still gets you. Like the palm reading at the very beginning. Every time I watch the movie, I still get startled by it, even though I know exactly what's going to happen.