Most mistakes in advertising are pretty expensive. Having to change something last minute, especially after it's gone to the printers, radio or TV stations can cost thousands of dollars. Having to redo something - tens of thousands.
Even seemingly small mistakes like writing something as $9.98 instead of $9.99 can put a major dent in profits. (1 million people paying 1 million pennies less really adds up.)
But the biggest, most devastating mistakes are those where you don't get any pennies at all. When people get mad about the content of your ads and threaten to boycott you.
People are not very forgiving of advertisers. So as a brand you have to be careful of what you say how you say it and who you say it to/about.
Here are some examples of misguided, naive and just plain ridiculous ads that have left the public in an uproar. And led to lots of losses - brands losing money, agencies losing clients, creatives losing jobs.
Tears.
The lesson here - watch yourself, watch your work. And remember you live in the world of advertising and it's easy to get disconnected from real life and real people. And it's easy to get caught up and miss red flags. The same way you can miss a typo after spell checking and proof reading twice. You can miss the fact that your ad is offensive.
