This one is a huge mistake I see businesses and service providers make all the time.
They spend lots of energy getting your attention and once they get it, they deliver VERY poorly.
A typical example is in the freelancing world.
If you are service provider of any type, remember that getting a customer to trust you and do business with you is only the first step.
What is REALLY the mark of your success is the fact that these customers come back for more.