When you're giving a speech, you probably hope that your audience is gazing at you in fascination because what you're saying is so interesting, and not because you've got something weird on your face.
The adjective interesting describes something that makes you curious, or catches your attention, but sometimes people use the word in a doubtful way when they are taken aback but want to be polite. Like if your grandmother looks at your new tattoo and says, "Well, that's certainly interesting!" Chances are she's not actually feeling very enthusiastic about your choice of body art.