My buddy bought a used backpack that looked fine in the photos. The fabric was clean, no rips. After one hike the hip belt padding was totally flat, just a thin piece of cloth left. You can't see compressed foam in a picture. He was stuck carrying all the weight on his shoulders for ten miles.

My buddy saved a ton booking a package deal to Mexico last year.

Funny enough, I was a total air pad believer for years. That whole "sleeping on a cloud" thing. Then I borrowed my buddy's old foam pad on a cold trip last fall. Woke up actually warm and without that weird lower back ache I always got. Now my fancy pad collects dust in the closet. That simple foam just works for me, no fussing with valves at 2 a.m.