I knew nothing about this topic in general, but elsewhere in this thread there was a link to a blog post about obfuscation methods used in a piece of commercial software. One item was a function that detects a breakpoint, obfuscates its boolean return value so you can't tell if it did, and makes the program hang when it does. Pretty neat.

I think your (and my) ignorance of such methods is evidence that they probably are reasonably effective, even though when explained, they're not quantum physics.