Thanks for the advice guys.
Funny thing happened to me last week though. I came by the GW store to buy some more paints for my basing project and I spoke to one of the guys who did the display models. He showed my how he washes and touches up... and he based with a Foundation paint (Mechrite Red), washed, and then re-applied the base. I knew Foundation color paints cover well, better than the Color paints, from my "tests" on the bases, but it never occurred to me to use it on my minis because I didn't like how "dark" Mechrite Red looks. However, when the GW guy did it, I was suprised how after 1 or 2 applications, the mini was clean again!
I've just finished a new mini with a base of Mechrite Red, a Thraka Green wash (GW guy says it was on the White Dwarf magazine as the "recipe" for the codex Blood Angel pictures), re-apply base, then 50/50 Mechrite Red and Blood Red. So far, I like the results in the sense that it gives me the dark colors in the recesses and red color on the armor and the application is easy and time-saving (and yes, I know lots have suggested this exact recipe, sorry for not recognizing it earlier), but I'm still not too happy with the brightness...
So, I'm still searching for the proper recipe, but at least now I know what I can use to clean up washes - Foundation paints!