I know you did, but as stated, those numbers by their own are not enough to prove or disprove anything.
The best way to test would be using a mod or cheat engine to propperly alter the atributes as needed, especially to lower something to 0.
Edit: to avoid having to argue the same things over and over I'll do the testing and post the results in a few minutes.
Link :
http://larian.com/forums/ubbthreads.php?ubb=showflat&Number=631817&#Post631817I created a new thread with the results on "Help/Tips/Tricks" to avoid it getting lost among these replies.
Short version is:
It appears that checks need X persuasion to pass, or X-1 persuasion and up to # of the relevant attribute.
Cheers.