I have recently given our bathroom a mini makeover (new colour paint on cabinets/new mirrors etc).
I always regretted having white grout with our white metro tiles and came across a grout stain/sealant which worked brilliantly on a tester patch I did.
Anyway, I've moved onto a larger area, and suffice to say the original white grout job seems to get progressively sloppier as I move around the bathroom. The dark grey stain only emphasises it.
So, the question.
Stop now, with one with the grey stained grout (above vanity area and sink), or carry on and accept that it's not going to look brilliant.
See diagram!