I've heard about executives going undercover to check out companies before they commit to taking jobs there.
"Before accepting the chief executive post at H&R Block Inc. last summer, Russ Smyth pretended to request help at six offices of the Kansas City, Mo., tax-return preparer. At each location, he recalls, he asked employees about their qualifications to handle his return and was impressed with their expertise." - From the Wall Street Journal.
I think this is a great idea for anyone looking for a job. If you're thinking of taking a managerial position at a restaurant, for instance, go in and order a meal. You'll get a taste of what you'll be working with!