On BlockChain.info, I have noticed a few transactions which send money to "Unable to decode output address".
For example, here is one: https://blockchain.info/tx/624928439d2f668bab9f4cc1d9c4d2bc62a9603d8109d73d4fff8cf3043b68bd
All of the ones that I have seen with this message have 0 Bitcoins associated with that transfer and then some other greater than zero amount of Bitcoins sent to a valid looking address. These weird addresses also have their money marked as "unspent". Do they ever get marked as "spent"?
What does this message mean and why are people sending Bitcoins this way?