It looks like these are scams.

It's probably possible to put any transaction history you like in there and make it look like the address associated with the wallet private key has a balance, but likely the key is fake.

Not sure about all the wallets, but at least some of those floating around have dud keys that don't unlock any Bitcoins.  Oh well.  It was worth a shot.  Trying to recover a wallet with known information that belongs to someone who can't decrypt it themselves for a share of the loot is probably a far better way to use some cracking resources.