I'd like to hear more about this, but for the record:
1. I have never used any of the codes listed here, either because they never seem to apply to the property I have in mind, or the GOV rate (for which I am eligible) is better. Sometimes the over-50 rate is better. I go for the deal I quality for.
2. For the periods I have negotiated a rate (because I'm going to be at a particulay property for an extended period of time), I negotiate with the GM of the place. I don't lie to him, I give him my best estimate of the business I can provide, and we go from there. If he decides that he can survive on $20/night (never actually happened), I won't dissuade him
. Sometimes (as in my current assignment), he won't negotiate at all. In that case I go somewhere else.
The point (and I think it's been discussed here many times before) is that misuse of codes for which you would not normally be eligible is an ethical grey area -- black for some and white for others. For me personally, I prefer to have things visible on the table -- otherwise, I would have nightmares about coming back one night and finding my stuff piled up in the lobby and some guy from Marriott security wanting to talk to me about back-billing and so on. Not a happy thought.