Why and how are fallacies used intentionally?

Answer 1

One example is in advertising. For example I saw a gym ad that said, "Turn your calves into cows." Now, that's a fallacy. We can't really turn our calves into cows.

Why is this used? To be creative with the words and visuals in the ad as to entice a prospective customer. To rise above the "standard" ad in hope of increasing profit.

Answer 2

I see fallacies inserted where situations prevent a comprehensive explanation or answer from being articulated. People who cannot resist expressing themselves or who may have pedantic values are probably the most common users of this intellectual 'bait and switch' maneuver.
Fallacies then become a euphemism for the unheard of answer, "I don't know." Fallacies generate more credibility than admitting that you don't know or simply guessing.
Your query is very open ended, yet, this entire topic is open ended also. Remember, too, fallacies are often employed collaboratively to support ones own public system of beliefs. They then become more convenient to support questionable rhetoric. Interesting question. I'm anxious to see more answers.
The applications have to be numerous. Good luck with your answers.

Answer 3

Turn on the TV and watch the commercials.
You will see intentional fallacies galore!
You will see:
False analogies[1](This product works for person X so it will work for you)
Appeal to false authority[2](Celebrity endorses some product)
Ad hominem[3](Used in political ads ALL THE TIME[4])
etc etc etc....

Why? To confuse watchers into buying products.

In the news you will see:
Correlation does not Imply causation[5](Claims like: listening to hip-hop causes violence, forgetting that kids who listen to hip-hop are likely to be living in poor neighborhoods to begin with )

Why? To be sensational.

Also watch some aggressive talk show, like O'Riley factor etc
There you will see Straw Man[6] used ALL the time.(for example someone might say "i am against the war", to which the host might respond:"so you are supporting the terrorists?")

Why? Again sensationalism -- improves ratings.

Answer 4

They are sometimes used in place of real arguments in the hopes that no one will recognize them as being fallacies, and take them as logic.