Ernie,
WNW's Lozenge is pretty well opague; I'd think just about any colour as a base coat for adhesion would fit the bill. With some of the A/M Products folks are saying the choice of a base colour is important as the decals are somewhat translucent. I have used WNW and my choice was for a medium Grey base coat, if only because it was a jar I didn't think would get used otherwise. I also ordered a fair amount of W&W Lozenge recently, all with solid white background, as I don't want any "bleed through" and will post shade over the Lozenge where necessary.
I believe the WNW Lozenge to be "Not all that bad" however I would definitely recommend a light and thin coat of overspray/wash in tan, grey, or a combo to tone it down. Otherwise it comes of as very stark.
Cheers,
Lance