Hi. I have worked in hotel industry for 2 years (at the front desk specifically), and can comment from my own experiences/observations. Generally, experiences that different guests have at one hotel are very different; even one guest has different experiences at different times with the same hotel. While hotels do try to give uniform services to all guests, many times Caucasians (or whites) get preferential treatment. Especially by the staff who financially benefit from them (housekeepers, bell-staff who receive higher tips). It's not a generalisation but I have seen it happen.
I don't know what is the solution to it, but in my opinion, high sensitisation of this staff needs to be put in place. Additionally, sometimes preferential treatment does happen (like you said) based on guest;s relationship with the hotel. In this, past (bad) experiences with the hotel, revenue generated by the guest, length of stay, overall profile of the guest and equations s/he has with the staff- all these things matter.
To answer your question, don't u have values/ideal behaviors/mantras for you hotel- the way most hotels have? As far as I know, all such rules emphasise on customer service and have anti discriminatory message- whether explicitly or implicitly mentioned.