With sad predictability, it would appear that another publisher has cottoned onto the "one save file" scheme experimented with in Resident Evil: The Mercenaries 3D. Namco Bandai is the unsurprising felon, with word that Pac-Man & Galaga Dimensions cannot have its saved scores and unlocked content deleted.
Dimensions has no scoring table, as reported by Wired. Your high score is all that's recorded, and it cannot be reset -- which naturally puts a dampener on its value as a secondhand title. This also means that once you've unlocked all the Achievement-like awards on offer, there's no chance to start over from scratch.
I previously argued that The Mercenaries could begin a new, unwelcome trend and Namco Bandai has all but confirmed it. It seems publishers are trying to use the "It's only a score-attack game" excuse, regardless of the fact that used customers might not want to compete against a stranger's score, and that new customers might want to start from scratch. What Capcom started is on its way to becoming a "thing", and I think that's sad.
So yeah, that's another 3DS game I was planning to buy but will now ignore. Cool.