Well, there's no critical failures or successes for skills, but a lot of GMs use them anyway (semi-common variant.) Mostly because its more fun that way... for the reasons you know well.
-TV
EDIT: This was just an example. I still dont think theres crit sucesses or fails on saves (unless theres sucesses but no fails. I've saved against things rolling a 1 before like DC 12 rolled a 1+13 and saved. I dunno... whatever.