The "deadly sins" are everywhere. People wouldn't bother with them if they didn't work.
It seems like an essential in a parent/kid relationship, it's used all the time...
"Mom, all my friends have cell phones, they say it makes life easier. You would get to call me whenever you wanted, don't you hate waiting around to pick me up"... that was me in 7th grade

"Made with all natural ingredients" and "sugarless" who doesn't fall for labels like these!

My favorite Deadly Sin was #3: Ignorance as Proof
I liked the conversation between the doctor and the patient. It was a good example. Since I'm involved with science it reminded me about research.

Strong Inference: it's where you try to disprove your hypothesis instead of proving it, because that way you look at all the possibilities. In the 1600's this scientist concluded that 'Plants eat dirt', he observed that after a few months the plant weighed more and the dirt weighed less. He didn't consider the nutrients or water or any other factor.

Heinrich tells us how to recognize and protect ourselves from them. but is it okay to use it sometimes?