I applied the dark streaking grime on a vallejo acrylic airbrushed base with a satin varnish coat on top.

The dark streaking grime turned a grey colour almost straight away and even when feathered with the white spirit, left a greyish water mark behind. I had to use vallejo airbrush cleaner to remove this.

So i tried again in an indescrete area and i found the AK 011 white spirit leaves a nasty rough texture once dry.

Do these enamel products react with the acrylics or the satin varnish???

What type of varnish did you use? If it was acrylic it should be safe... I have never had any problem with these kind of products, or modelling thinner with oils, over acrylic base. Maybe it was not completely dry?

I used Vallejo satin varnish days before i applied the AK products.

It really leaves a horrid finish.

Quite strange... it should not affect at all.

Can you try another thinner and see if the paint reacts the same? Also test the thinner over bare paint so you can see which one of these products is causing the problem.