Hi, as you may know, VaM is using the Genesis 2 figure.
So only textures made for Genesis 2 will fit.
What is not so well known: There are even different "uv maps" within the Genesis 2 generation.
A texture made for "Base Female" will not fit to "Ghia, "Michael" will maybe not fit to "Darius", and so on.
VaM has included some of them with the differnt "skin sets", even one for Genesis 1.
You can find the compatible UV map by looking at the skin selection tab. It is written somewhere there for each skin.
I don't exactly know what you mean with "terrible", but if you can see black stripes or even black parts, then it is an issue with the wrong uv/skin. If it is something completely else, please add an picture, so we can have an idea.