This post on the Beyond Bullet Points blog, "Ten Ways to Give a Bad Presentation," cracked me up.
#6 made me laugh out loud, and it's one of my major pet peeves:
"Capitalize everything. That's right. Sentences Should Be Like Book Titles. BETTER YET, DO THIS AND CAPITALIZE EVERY LETTER. That should drill your words into the audience's heads."
I Don't Know About You, But Sentences Capitalized Like Book Titles In Slide Shows Drive Me Crazy! Why Do So Many People Do This?
People suddenly lose all reason when they design slides. Rules of grammar and spelling we've known since elementary school, not to mention good old common sense, fly out the window.
Read the rest of the list, and let me know in the comments what other ways you can think of to give a bad presentation.