I for one make it a point to only use codes for which I qualify (m11 etc.). I've never used a code assigned to a specific corporation.
My son, on the other hand, (also a plat) is in a business servicing a number of corporate code holders and has been encouraged by a couple of his clients to use them. In other words, he's in town specifically to provide services to "xyz company" and has always stated this when checking in.
The only time he was questioned was at the full-serve Marriott at Overland Park, KS (Kansas City)....where he was working with Sprint. He was asked to produce a letter to that effect from Sprint. He provided that the next day. It went into the hotel's database, and he hasn't had a problem there since.