I've deleted tw comments till now from the few that I have received on my blog.
The first was about the commenters preference of what size a woman's twin parts should be.
The second compared my website to beggar's vomit. No, not kidding. The commenter actually said that I had a terrible website and the colors were worse than beggars vomit. He left his name and email of course. I contacted him for some REAL feedback and also informed him that beggar's vomit probably looks the same as anybody else's only to find out that the email address belonged to some American girl's. She was so apologetic that I didn't even tell her that it was probably just a random guy who had typed a random email address.
I don't really feel any remorse at deleting those two comments. I even go back and read the american girl's apology email if I feel like a laugh.
I also occasionally delete double comments because first time visitors don't read that their 'comment is held for moderation' and end up repeating the comment a second time right away. I don't really consider this deleting a comment.