What's so disturbing about serial killers?

So this woman comes in the shop a couple days ago and asks about this graphic novel I have about a very famous serial killer.

I let her know how it is. I tell her it's complicated. It's long. It's disturbing.

But it's really well done, well researched.

She buys said graphic novel.

Two days later (This morning, in fact) the phone rings:

ME: "::Standard phone greeting!::"

HER: "Hi...this is Jane, remember that book I bought the other day?"

ME: "Yup."

HER: "Well, I don't like it. It's long and complicated and disturbing."

ME: "You saw how long it was when you bought it....and it's about a serial killer, didn't you think it might be disturbing?"

HER: "Not the parts before he became a serial killer."

ME: "And how was it complicated?"

HER: "I don't know...I only read ten pages."

ME: "Bring it back in for a full refund...we always around."