Anything that can be accurately preceded by the adjective 'gratuitous.'
In a little more detail: I don't squick easily for things like sex or violence, so long as they are shown to be what they are, and not romanticized. As long as the consequences remain intact, as long as the issue is explored and not tacked on, I'm okay.
And -- warning for personal pet peeve -- I also have a bit of a problem with the too much angst at once thing, where a protagonist is tortured, and then raped, and then her country goes to war and she's on the front lines, and then she's put in jail, and then her husband cheats on her with her best friend, and then they both die, and then she's tortured again, and then she's briefly pregnant but sadly loses the child, and then her dog dies and her truck's stolen and maybe she loses an eye. There's a limit to how much is really necessary when it comes to pain, death, torture, loss, etc. This actually ties in with the above: you have to have space to explore the effects of one horrible thing on your protagonist, or two horrible things and how they balance out, and then they can lead to three, four, or five. But sometimes it just gets silly, and then I'm not sympathizing so much as snickering.
In a little more detail: I don't squick easily for things like sex or violence, so long as they are shown to be what they are, and not romanticized. As long as the consequences remain intact, as long as the issue is explored and not tacked on, I'm okay.
And -- warning for personal pet peeve -- I also have a bit of a problem with the too much angst at once thing, where a protagonist is tortured, and then raped, and then her country goes to war and she's on the front lines, and then she's put in jail, and then her husband cheats on her with her best friend, and then they both die, and then she's tortured again, and then she's briefly pregnant but sadly loses the child, and then her dog dies and her truck's stolen and maybe she loses an eye. There's a limit to how much is really necessary when it comes to pain, death, torture, loss, etc. This actually ties in with the above: you have to have space to explore the effects of one horrible thing on your protagonist, or two horrible things and how they balance out, and then they can lead to three, four, or five. But sometimes it just gets silly, and then I'm not sympathizing so much as snickering.