Ah yeah the GW Dry paints are actually just pigment with no medium, meant to be used with stiff bristles for drybrushing.
I tried one ages ago and wasnt a fan, I'll stick to wiping the paint off on a paper towel.
I have a few Vallejo paints, not a fan of their washes though, I think GW make the best washes currently.
I am still using diluted inks for washes. I do have a few new ones, but find them not as controllable for pigments as the inks. Some also seem a little grainy when they dry. To be honest, have not tried the Vallejo washes. I do like their transparents though!
No brush in the world was picking up pigment from the "Dry"pot I opened. It was not even staining the stirrer I attempted to use, thinking it might have separated in the pot. It is soft, maleable plastic.