How does Ally Carter use imagery in I'd Tell You I Love You, but Then I'd Have to Kill You?

Imagery:

"Let me lay it out for you. Best-case scenario: all the girls go ga-ga for him and lose focus, which I'm sure is very important at the Gallagher Academy. Worst-case scenario: he's an inappropriate-conduct case looking for a place to happen. The only people who teach at these places are freaks and geeks. And when you've got a headmistress who looks like that, it's easy to see what Mr. Eyecandy was hired for... You're the Gallagher Girl. If you can't figure that out, then who am I to tell you."