I've flown first class often enough, and I've always been treated very well, despite low or no status. I've never noticed that they treat me any worse because I upgraded or used miles for my ticket. In my opinion, a first-class passenger should be treated like a first-class passenger, period.
If you're in a service-related business, and you don't like your employer, don't take it out on the customers. If you don't like your employer, find another one!