For any inroom coffee maker, I run through plain water first. Then I use bottled water and my own coffee (I travel with ground coffee and filters - practically live in hotel rooms most of the year) This makes a good cup of coffee for me.
There are a few hotels which do serve either Seattles Best or Starbucks as their in room brand; most others use a generic provider. I don't know if it's the filter they use, or the coffee, but it's not the water in my case.