Well, I personally assume an unweighted distribution unless otherwise specified. Based on your point, I could choose to use 99% PC and 1% for all NPCs (regardless of number) and call that RAW.
Actually, our example involved a bear using Improved Grab. Are you saying that it wouldn't have called for the percent chance to hit the bear then, or is that just due to the way you "houseruled" it?
A creature with Improved Grab can take a -20 penalty to Grapple checks in order to be considered ungrappled.
SRD said:
Improved Grab: The creature has the option to conduct the grapple normally, or simply use the part of its body it used in the improved grab to hold the opponent. If it chooses to do the latter, it takes a –20 penalty on grapple checks, but is not considered grappled itself; the creature does not lose its Dexterity bonus to AC, still threatens an area, and can use its remaining attacks against other opponents.
If the bear doesn't take the penalty, then he's grappling for all purposes (including hitting the wrong target). If he does take the penalty, then he's not considered to be grappling.
