My experience was that the model that I was able to see had a strong mirror effect that counteracted the effect of the Vantablack. This was the Perpetual Moon Vantablack model. I found a photo on the internet that shows this effect.
But maybe that was only with the first models and was then improved? I don't know exactly how the crystal was built on this model I had seen and if it had an inside antireflective coating or not.
Best Thomas