There's nothing wrong with liking Legally Blonde: The Musical. My girlfriend loves musical theatre, both participating and watching (as long as it's good, she hates Chicago with a passion because according to her it's terrible. I've never seen it so I can't judge), and she's looking forward to seeing it. She's looking forward to seeing Wicked more, but that's besides the point.
As for the actual topic, I think the closest thing I have to a guilty pleasure is High School of the Dead. The anime. Which needs to get another fucking episode right fucking now.