The bonus for a 20+ perception score, according to the manual, is the ability to detect things that are invisible. Does this apply to traps? It would seem ridiculous if that were the case, as it would pretty much obviate the need for the Spot Traps skill altogether. On the other hand, traps are the only thing I can think of that are invisible (aside from enemies if you plant that one cursed ring on them), so if the bonus doesn't apply to them, what good is it?
And on a related note, what kind of skill/training level would I need in Spot Traps to get through the Black Mountain Clan Mines without totally obliterating my party's gear? I'm assuming scrolls of Sense Invisible aren't going to do me a lot of good as a technologically inclined character.
According to this, there *are* invisible enemies out there. http://terra-arcanum.com/phpBB/viewtopic.php?t=5868&view=previous&sid=feec6e8ce187212640a1853050ab0461
"And the 20 perception is correct too. You can sense invisible monsters - not traps and such, which should be detectable long before you reach 20 PER.
The invisible creatures appear as transparent monsters but you no longer have any penalties to hit them.
I had a technologically adept character, albeit only at +20 rating and not all the way, the Detect Traps scroll still worked so my guess is the higher your tech rating, the more likely the scrolls will fail. If in doubt, save your game, and try out a Scroll in the BMC mine to see if it works.