I have a slightly brighter VW85 and to all not seeing amazing black levels, if your room is white or light colored walls, and you have lights nearby when watching anything, you'll crush the black levels, as the room will be illuminated even dark scenes. Let's say the ambient adds 50% of light to a dark scene, and you don't need much light for that to happen, then if you had 1/15,000 native contrast. But the already present light (let's say it adds a constant light equivalent to 2000 times the value of the darkest color the projetor can offer), then...when you factor that in, you will have 2000/17000 (just adding 2000 to both terms) or a 2/17 contrast rate...which is horrible and why it looks like crap. Now suppose your white walls and screen choice reflects a lot of light. Suppose you get back 25% of the screen brightness back to it as it bounces on walls, in terms of average light. Now, what you have is a relatively good black level when the scene is extremely black with just very few parts that are very bright, as you eye sense the contrast, as that particular image is overall dim with some local bright parts. But when you have more white, lots more are bounced back. The whiter the scene (larger % of image area is bright white), the more that is reflected back. So in those scenes, you will get the 25% of light added to the scene. Suppose your projector can do 16,000 native there. 25% back means you add 4,000 back. So the light will be in the relation of 4,000/20,000 (I am just adding 4,000 to both terms). That's 1/5 contrast. I am exaggerating a bit, but even if it only adds 5% back, you get 1/500, as the baseline gets crushed by that 5% increase in light. This is why even with caves, if the walls are white or reflective, you get extremely average contrast.
In the case of having ambient light, your only choice is to get a light canon that make the ambient light in relative terms much better, Doesn't matter if the projector is 1/2,000 as long as it can eclipse ambient light, you'll see a huge improvement. On the white walls or reflective rooms, your best bet is using a gain screen that will make sure the light is reflected backwards, and that overall, you'll be dimming the projector a lot for correctness. That will reduce the amount of light bounced back (there will be much less light bounced, and that coming from angles will not be reflected much, and that reflected from the back will be less as well. You can only enhance contrast in light colored rooms where you see "the room becomes well lit in bright scenes" with a different screen, or by reducing the screen size (and lowering lumens you'll need less for a smaller screen) or by finding ways to make the reflections go away (which means walls that will absorb, not reflect light) or only watch horror movies with little light on them.
All in all, if you have a room with poor light control and/or reflective walls, your investment will not shine in terms of black levels. You'll need to invest more in the future. And I mean, it will probably such at having great black levels.
I wish there was a tool to estimate your contrast rate given a % of reflectivity as measured from having all black walls, the kind of screen, the projector native CR, the max ansi lumens, and the ambient light in some measure. It will help you compare real case scenarios.
btw, my walls are white and I see blacks crushed in very lit scenes. On very dark scenes it excels. And I can't watch anything during the day. On the other hand, it's perfectly ok for me right now, and I think the 85 does a good job at keeping me happy (but I am not yet making it proud of itself).