You may have guessed it, rolling up one of these monsters is basically impossible. The best result (certainly not a systemic issue, just a bunch of lucky rolls) is that 16 out of 1 million thieves are this awesome. That's not a lot, certainly not enough to ever actually see one of these characters in your games. But let's scale back a little bit: A character is pretty decent already if you get a total of +3 or more in terms of modifiers (and pretty bad if you get -3 or less) so what's the chance of rolling that? Better it turns out:
|Class||Chance >= +3||Chance <= -3|
It's a little surprising (for me anyway) that human characters have a better chance of being "bad" than "good" according to my simulation. Demi-human characters, on the other hand, have a better chance of turning out "good" as it were. Halflings are especially lucky in this regard, so maybe the next time you roll up a character who actually qualifies for being a Halfling, you should really go for one of those little buggers?
(Sorry, I am sitting at my dad's weird Windoze box in Germany, so I don't have access to my usual Python toolbox of visualizations. I was going to plot the actual distributions for you, alas I'll have to add those things at a later date. I hope you still enjoyed reading what I have.)