Indeed. I just checked and some of my wallets have gotten spammed also. All of these cold storage wallets were created carefully by starting up a wallet-less bitcoind then carefully wiping everything. They've been deeply off-line ever since. They would have been created and stored in Q3 2011.
I probably have checked the balances on blockexplorer back in the day.
I have created a Google spreadsheet which queries blockexplorer when it still worked and more recently blockchain.info for balances. Derived from coblee's work. I check it occasionally. It is shared with noone.
However their addresses have been public ever since 2011. Because p2p blockchain.