Recently a tweet from Doug Laney of Gartner has been retweeted a lot:
As most analogies it may fit or maybe not fit seen in different perspectives. Actually rental cars are probably some of the most washed cars as the rental company wash and clean the car between every rental.
In the same way as rental cars usually are quite clean I have also found that sharing data is a powerful way to have clean data as told on the page about Data Quality 3.0. This is also the grounding concept behind the instant Data Quality solution I’m working with, where we have just released our iDQ™ MDM Edition.
Liliendahl on Data Quality 
A better analogy is: No one ever maintains a leased car. After all, in less than two years, you are just going to turn it in.