It could turn out well for them; all these people thinking they are hacking the system to pay $150 and save $200 when in fact both sets are actually worth $15 or less.

I'll bet none of them could tell the difference between with foam and without foam, either.

I doubt this is true. See those holes near the bottom / on the back of your computer speakers? Play some music and shove your thumb in them while it's playing. You'll hear the difference.

Air needs to move for sound to exist, even in the direction away from your ear. If stuff's in the way, the sound's going to be muffled.

There is a huge difference. I have a pair of Grados with hard, open foam pads. They came with soft, closed foam. The closed foam covers the speaker and you get muffled sound. I am not an avid audiophile but I have mixed music for my church some years in the past.