Two weeks ago, I realized halfway home that I'd miscalculated the tip. So, the next time I visited I apologized for that miscalculation and left a tip big enough for that visit as well as the previous one.
And ever since, the staff has been even nicer to me: free miso soup, a free piece of albacore here and there, automatically asking me if I'd like "the usual," greeting me by name, seating me right away, etc. This, despite the fact that averaged over both visits the tip amount was perfectly normal.
Similarly, when I worked as a sysadmin for a web hosting company, it often seemed as if customers were happier as the result of something going wrong: in contrast to normal operation (during which the service the customer is paying for is essentially invisible to them), a failure provided the opportunity for the company's sysadmins to demonstrate speed, professionalism, and excellence in resolving the problem. Granted the following isn't something we ever did, and it isn't something we would have ever considered ethical, but while employed there I did often wonder whether it might be an effective customer-satisfaction tactic to rig a failure that we were all instantly prepared to resolve.
I think if I were to ever write one of those faddish business management books, its title would have to be The Art of the Strategic F**k-Up.