Every brand has a 'circle of acceptability': a mental corral within which the brand's advertising would be believed and deemed acceptable by the brand's target audience. By this, I mean the kind of advertising that is appropriate for a zit-faced surfer at Bondi Beach is not necessarily right for the 64-year old grandmother losing sleep over her medical bills in Ang Mo Kio.
Push beyond the cicle, and you'll end up with credibility snap.
In a previous life, I once had a manager who used a complaint about me to deliver one of the most inspiring lessons of my career. I was heading a regional marcom team at the time; and our legal team had just hauled me up for making one of these borderline claims for our product in an ad. I expected to get chewed up when my boss summoned me to his office. Instead he said, "David, if you're not getting hauled up at least twice a year by Legal, you're not doing your job!"
I knew from that day on that he wanted me to push the envelope, to stretch the boundaries of our brand's circle of acceptability with some edgy work, so that we'd get noticed, and gain a bigger bang for our buck. And I've nudged all my teams since then to do the same: Not to aim for the safety and comfort of the centre; but to skate at the edge without falling over.
Over time, your brand will loosen its collar; and your audience will become comfortable with different shades of its character.
Who dares, wins.