It’s a ritual repeated at parties from Georgetown to Old Town. After behaving like grown-ups all evening while greeting acquaintances (“Mrs. Obama! Nice dress!”), nibbling undersized crab cakes and quaffing cheap wine, guests dash for the goodie-bag table, grabbing and — right then or later — pawing through their gratis loot-sacks like a pack of over-cupcaked toddlers.

“People sometimes skip a party if they don’t think there will be a good gift bag,” says Barbara Martin, principal at D.C. public relations firm BrandLink, which often hosts events. “They love free stuff.”

What’s inside the shiny bags or recycled logo totes? Everything from the somewhat fabulous (full-size bottles of perfume, store gift cards) to the forgettable (bottles of vitamin water, postcards hawking restaurants).
But why, if you’ve just been to a nice charity gala/friend’s wedding/store opening, should you expect freebies in addition to a good time?

“Some people or businesses think it’s proper etiquette to thank someone for coming with a gift,” says Arlington event planner Vicky Choy. “If it’s in the party-thrower’s budget and they want to, I say ‘Why not?’ ”

After all, it’s a long-standing tradition to send revelers into the night with a little something: In first century B.C., Cleopatra doled out such parting gifts as gold sofas and live gazelles. And celebs notoriously leave awards shows with swag including trips to Australia and even, for this year’s Academy Award nominees, a $5,000 “Vampire Facelift” — whatever that is.

Still, for less stratospheric occasions, loading attendees down with junk amounts to an entertaining foul. “I don’t need a bag full of paper or another key chain,” says Kimberly Robinson, 29, founder of D.C. bakery Makin’ Whoopie and a frequent partygoer. “I understand that these bags serve a purpose — to promote a business or commemorate an event. But if you’re going to do one, think about what people would actually use.”

This means yes to things that can be consumed (chocolates with a store logo on them, a bottle of wine emblazoned with a pic of the bride and groom) and no to stingy 10 percent-off paper coupons from boutiques (most people lose ’em or don’t use ’em) or Hobbit-size perfume samples (one squirt won’t tell you if you love Eau de Hipster).

“If you’re marketing via a goodie bag, you leave a bad impression if there’s nothing good in it,” Martin says. “Make people remember you.” Robinson, for instance, recalls an attention-getting takeaway: a fancy metal cocktail shaker stuffed with information and goodies. “It was fun and useful,” she says.

Some say that just attending a party is a treat in and of itself. “Guests need to go to events with clear, pure motivations, either because they believe in a cause, are interested in a business or they care about the person giving the party,” says Northern Virginia etiquette consultant Rhoda Wheeler.

Or, as Robinson says, “What I’d love is a thank-you note for coming at all.”