We generally like to encourage people to work where they want, so non-compete agreements only survive court scrutiny if they are narrow in scope. Starbucks may have its work cut out for it. The coffee chain has sued a former executive in Washington state federal court for going to work at low-cost rival Dunkin Donuts.   Starbuck claims the man, Paul Twohig, signed a non-compete agreement that prohibits him for 18 months from working as a manager at any Starbucks' competitor within 50 miles