1. The "Dear Idiot" letter Be careful where you get your data – it may come back to haunt you. This tale of terror comes from the customer call center of a large financial services institution. As in nearly all help desks, service reps take calls and enter customer information into a shared database.

This particular database had a salutation field that was editable. Instead of being constrained to Mr., Ms., Dr., etc., the field could accept 20 or 30 characters of whatever the rep typed. As service reps listened to the complaints of angry customers, some of them began adding their own, not entirely kind, notes to each record, like, "what an idiot this customer is."

This went on for years. No one noticed because no other system in the organization pulled data from that salutation field. Then, one day, the marketing department decided to launch a direct mail campaign to promote a new product. They came up with a brilliant idea. Instead of purchasing a list, why not use the service desk database?

So the letters went out: "Dear Idiot Customer John Smith."

Strangely, no customers signed up for the new service. It wasn't until the organization began examining its outgoing mail that it figured out why. The moral of this story? 

"We don't own our data any more," says Arvind Parthasarathi, vice president of product management and data quality for data integration specialists Informatica. "The world is so interconnected that it's likely someone will pick up your information and use it in a way you never anticipated. Because you're pulling data from everywhere, you need to make sure you have the right level of data quality management before you use it for anything new."

What constitutes the "right level" will vary depending on how you use the data. "In the direct mail industry, getting 70 to 80 percent of your data correct is probably good enough," he adds. "In the pharmaceutical industry, you want to be at 99 percent or better. But no company really wants, needs, or will pay for perfect data; it's just too expensive. The issue always is, how will it be used and at what point is it good enough?"