A redemption without going through the process or taking any effort is not redemption at all. In other word, the honor of model citizens has to be earned, just ask Jack. This was why I previously said Xander's "redemption" was poorly executed as Ben and Kristen's.
LOL didn't Sarah cheat on Rex with his own brother and almost had sex with Eric when Xander walked in? Wait, maybe you are right, a serial-cheater and con-artist getting together, what a wonderful combination.