I think it depends on the hotel and the rate itself. I do believe that sometimes the rate is supposed to be for employees only, no contractors. Other hotels may have a negociated rate that includes contractors.

Your best bet is to contact the hotel and ask. That is what I do. I used to work as vendor for Continental airlines down in Miramar, FL. The Harbor Beach Marriott would let me use the Travel Industry rate to stay there. And back then they had a very nice discount on that rate. The only thing they asked was that I get a signed letter on company letterhead stating that I was doing work for them that week. But I always checked with the hotel beforehand to verify that that was acceptable. I have asked other hotels the same thing and they didn't want to let me use the Travel Industry rate if I wasn't a Travel Agent. So it depends on the hotel.