I highly doubt I'm the only one with a corporate hotshot relative who allows family to use the codes.
The only legitimate reason the hotel needs is that the company is giving permission, for whatever reason, for that individual to stay on the corporate rate. Since my uncle is THE guy to ask permission from, I see that to be a perfectly legitimate reason, and the paperwork (that so far has never actually been produced) would not be fake.

But again, I was only attempting to share my experience, not derail this thread. Obviously YMMV, but from my experience, so long as the hotel is not overbooked, and so long as you go in with a friendly smile and an air of confidence, they usually won't cause any problems.