Eh, a ten will give you about a 50/50 roll if something is "easy," and only about a 25% chance if something is "medium" difficulty. Sounds about right for me.

Am I gonna shut my damn mouth when I should? 75% of the time, no.

10 is average for an adventuring hero. Not necessarily for most "civilians" if you want to call them that.

Edit: I stand corrected. Must have confused it with some other system or an older edition.