Like everyone else said, hairspray works great. But, whenever I have a set-in stain (or the item has gone through a hot dryer), I've used Fels-Naptha to remove whatever the offending mark was. It's worked on ink, mustard, oils, blood, etc. They actually still carry it at my local Wegman's in the laundry aisle -- $1.00 for the bar. Cheap and cheerful, and doesn't leave a ring like some sprays can.