It wasn't until the Wii U launched that we found out accounts and information registered on that console would be staying on that console. Sounded bad at the time, but there might be a bright side to the whole mess.
There obviously haven't been too many people buying one of the machines pre-owned in its early days, but one person who claims to have done so is NeoGAF poster DSN2K. Who also says that, having bought the console, they were able to download, for free, games purchased by the machine's previous owner.
While the Wii U appeared to have been wiped clean, after visiting the Wii U eShop, DSN2K says that some games, once you clicked on their store entry, didn't have a price. They instead said "redownload". So far, they claim to have gotten Trine 2 and Nano Assault without paying a cent.
While it sounds crazy that something like this would slip through the cracks, remember, the internet is a bold new frontier for Nintendo. So there's always the chance this could go on the list marked "stuff we didn't think about but wish we had". We're checking with Nintendo PR for comment, and will update if we hear back.