Just yesterday, actually, i was playing fallout 3, wearing the Chinese stealth armor in the train tunnel to Adams AFB, on of the goddam sentry bots rolls by, then turns around and starts spraying me with the laser machine gun.
This is with me at 100 sneak , with the 40% stealth field generated by the armor, and the 15 bonus to sneak, in a dark room.
It wasnt really scary, in the sense that you gonna have nightmares, but it startled me because i thought it was impossible for the bot to know i was there, let alone damn near kill my ass.