“The problem with first impressions isn’t that they're not important (They are important! They're critical!), but that we have no idea at all when that first impression is going to occur… That’s why authenticity matters.”
Seth Godin, numero uno marketing guru, explains in his 2005 book, All Marketers Are Liars, why authenticity and consistency matter so much to your brand or business.
The customer is not a passive consumer of your marketing; they interpret it the way they want to. Or as Seth says, "The reason authenticity matters is that we don't know which inputs the consumer will use to invent the story he tells himself."