Want to position your advertiser as a hero? Create a straw man.
Invent a competitor; create a fanatic, a lunatic, an eccentric, a devil's advocate, an overblown skeptic, or an out-of-control situation.
Don’t make the examples so unbelievable that the audience discounts the point you’re trying to make. For example, if your client owns a car wash, don’t create someone who sandblasts his car whenever it gets dirty. But you might have a conversation with someone who has collected a year’s worth of dirt on his car and doesn’t even remember the original color, or a great procrastinator who waits for a rainstorm to wash off the accumulated dirt.
Instead of creating cartoon characters, go for someone who seems almost normal, but has unexpected quirks. This distinction you make will be a judgment call, a fine line, and examples may not explain it adequately. Think loveable, quirky, and believable. Exaggerate but don’t go so far out of the realm of the listener’s experience, that he doesn’t believe the claims of the advertiser. Have the characters in the spot say outrageous things in a normal tone of voice.
Ask yourself: who do I know who has bought this item, used this service, had this problem (that can be solved by the advertiser)? Now what personality traits do they have? Which of those traits would be most entertaining if they were exaggerated? Which of those exaggerated traits would best demonstrate the benefits to the listener? What kind of situation can I create that would make the best, most compelling story?
Your straw person could be someone who hangs out at a car dealer’s showroom because the sales people understand him better than his family does; a guy who brings his know-it-all brother-in-law into the hardware store to meet Hank, the owner, who really DOES know it all when it comes to DIY projects; or the woman who calls the advertiser with major complaints, only to have each one explained as a misunderstanding—giving you lots of opportunities to describe benefits.
Your opportunities for creating straw men are limited only by your imagination. Start baling.