How do people know somebody isn't already on their way to pick it up? If she takes it down the first time somebody says they'll take it... she'll just have to list it again when they don't show up.
Even if something is free... I'm not wasting my time moving a playset (getting helpers, a truck.. etc) if the seller won't communicate 🙂
I've sold (and bought) enough stuff on facebook/ksl/etc to know that the polite way to engage a seller is to say "Hi, is your item still available? If so.. I'll take it!"