What's in my bag right now? My big wallet, cell phone, lipstick, lip gloss, hearing aid batteries, face powder, sunglasses case, a bunch of pens (always have pens on me), and . . . my Nordstrom credit card bill. That's a lot more streamlined than usual, but I recently switched bags so I'm starting fresh.
Edited to add: Oops, I forgot ~ always a small bottle of Purell.
Edited again to answer the question of how often I clean out: I clean them out either when a) too many papers (receipts, maps/directions, grocery lists, etc.) get shoved in and it's driving me crazy, or b) when I switch bags, which isn't as often as I'd like to. Bag switching for me is totally random, but I'd like to do a better job of coordinating bags to outfits. Someday!