The free stuff factor we learned in college never gets old. Most offices have an office supply cabinet where they keep all the extra pens, masking tape, folders, etc. And even though the entire contents of the cabinet cost twenty bucks, you still hoard as many supplies as you can, just because they're free. But guess what free crap? Still crap.
Some companies make stuff with their names on it. That makes sense if these things are being given out as promotional items. Not if they're being used around the office. You spend 40-50 hours a week in this place already, you probably have an e-mail address with the company name, and you might even have business cards. But in case you forget where you work, you can check your tape dispenser.
Everyone I know goes through at least a box of pens in a year. I used to think it was because people are constantly losing their pens. Actually, the pens are right in front of us. But after a week, they're so chewed up that you can't tell they're pens anymore.
Office supply stores are fun because they make you think of uses for products you never thought you needed. Like the desk organizer that organizes your other desk organizers.
Businesses have to make a choice. Either they lose money paying someone to do inventory, or they lose money paying for replacement supplies. So most of them don't bother to do inventory, because if they're going to lose money, at least they can help raise company morale with free pens.