Stick a used game in the PS Vita and it'll politely alert you that you won't be able to earn any trophies unless you link the original player's PSN account to your system. That's pretty obnoxious, but to be fair, it's more likely a symptom of the Vita's one-account-per-system limit than an insidious plan on Sony's part to prevent you from buying used. Then again, maybe it's both.
Either way, Pocket Gamer's laid out the steps you'll need to circumvent this. It's pretty straightforward, actually: touch and hold the screen for two seconds and click on the ellipsis (…) that pops up next to the offending application. Select "Delete," which erases saved games and trophy progress on the game card, then "Ok."
That's it. And the previous player's account will still hold a record of his or her trophies. Likely the only way we'll ever know if this was meant to be an intentional way to discourage used game sales is if Sony patches this fix out of the system—let's hope they don't.
Have you run into this issue? What did you think? Let us know in the comments or on Twitter.