Absurdly high skill levels

[Zed]

I'm curious at what point do skill levels become so high that no about of penalties short of impossibilty can lower them past the usual critical failure point?

Areas of interest:
Combat skills
Social/Influence Skills & Reaction Mods
Job/Professional skills
"Knowing stuff" skills
physical action skills (jump, lift, climb, etc)

At what skill level does the effect from such a skill use become 'cosmic-like'; an absurd effect; the realm where you start pulling off deeds that border on 'powers' (Social skills working on mindless undead for example)?

I'm asking about RAW penalties and there limits. A GM can always bust out non-RAW super high penalties if needed to keep his game in the 3d6 happy spot. What is the point where RAW no longer suffices?

~Z