Despite what you might think, unlike Facebook, people do not really give a damn if you unfollow them on Twitter. Stop being such a wuss and just unfollow people whose tweets you don't want to see. If they're the rare case who gets back to you and asks you why, you can then provide them with valuable feedback.
I have an old friend I follow on twitter who tweets way to much garbage and I want to unfollow her, but I know for a fact she uses an unfollow tracker, and I KNOW it'll spite her. I wish there was a way to mute people right in Twitter.
Anyway, it's not like you're calling her baby ugly, it's just Twitter.