First the fail metal flake polish.
We have Copper, Gold and Silver shredded glitter over black
As you can see for the gold and copper the colors bled a bit. I think the silver did the best mainly because the pieces were smaller in general. The gold and copper I had to fish for which I hate so I'll probably toss these or if you want them I can send you.
The one on the Left is a tarnished silver color it is opaque in 2 coats but layers over dark colors well. The other is a blue creme with silver shimmer. It can be layered too but I like them both on their own.
Now I am not sure if the win and fail is simply because I have been moving personally away from glitter polish. I still like some, but I am much more selective about which glitter polishes I will actually buy. I just don't use them often and I really have to love a glitter polish to use it these days. Oddly enough it was glitter polish that first got me into nail art in the first place. Because the awesome thing about most well made glitter polishes is that they look good no matter what on any length of nail in any condition. I know that most people can tell my nails are not in top condition and believe it or not they used to be much worse. So a lot of creme or metallics didn't look so great because you could see the dings and the ridges in my nails. I still have dings and ridges but not as bad as before and some metallics and cremes are still too unforgiving for me.
I think if I make some more polish I will stick to shimmers or cremes. I might try a matte glitter polish but we shall see :)