I find that coffee made at any of the Anaheim hotels tastes really gross to me and I think it has to do partially with the kind of coffee and partly because of the water. I can't drink tap water at Disneyland so next trip I am going to try using bottled water for coffee and see if that improves the taste!
I'm going to preface this by saying that everyone has a different opinion as to how "great" coffee should taste.
I don't think you can make a good cup of coffee in the room with the keurig machine. I know that makes me sound like one "those," the self-proclaimed snooty coffee mavens, but the reality is that I can find a good cup of coffee in almost any location. I have not, so far, had much luck at DLR, whether it's in the room or in the parks with the exception of some of the fine dining locations and Starbucks. I am not saying SBs is the best ever, but it certainly beats Joffreys. Not sure why the fine dining places have better coffee, but guessing they may use different brewing techniques and coffees OR maybe they've just greased the way beforehand with some excellent liquor. There is also the cream...
If you're like me and want cream in your java, very important to taste is the type of cream they serve. If you're getting one (or more) of those little plastic cups with a peel-off lid, that's not cream. It tastes gross. Yeah, better than coffee-mate, but not real cream even though it says real cream. In the finer places, you get an actual little pitcher of half-and-half. Big, big difference. Real=yum. Plastic cup=tastes like barf.
So...to me, the type of coffee and the type of cream make a huge difference. Most of the fine dining places have good coffee, whether due to the water they use, the brewing technique, the coffee brand, the cream, or all of the above I don't know.
Edited to add: last trip, I mobile ordered coffee from SBs and got a cup of half-and-half to take back with me. It did improve the room keurig coffee quite a bit.