This might be the simplest possible explanation of customer satisfaction.
Dissatisfaction occurs when salespeople and marketers tend to try to amplify the first part (what you're promised) while neglecting the second.
The ability to delight and surprise is at the core of every beloved brand (product, politician, teenager…). Overhype and shady promises will undercut that before it even has a chance to get started. Yes, of course you have to make promises to earn attention and trial. The mistake is when you put more effort into the promises and less into what you deliver. Promise a lot but deliver even more.
[One really important amplification: Research shows us that what people remember is far more important than what they experience. What's remembered:
–the peak of the experience (bad or good) and,
–the last part of the experience.
The easiest way to amplify customer satisfaction, then, is to underpromise, then increase the positive peak and make sure it happens near the end of the experience you provide. Easy to say, but rarely done.]