What makes this different from simply putting ads in 404.shtml etc?
I don't get it either.
What makes this different from a standard error 404 page?
Why would every visitor each visit get at least 1 error page? If you are causing errors or simulating errors to drive users to a page, why would you want to do that?
If there isn't any content on the error page, what are you using to influence the type of AdSense ads that display?
No offense intended, but this looks like a good way to get an AdSense account banned.
Actually, AdSense isn't allowed to be shown on error pages.