I've applied flat lacquer to the whole ship, and it caused the decals to haze.  I consulted the Model Master product manual and confirmed that I didn't do anything wrong (that I know of!), it was just doing exactly what the book said it wouldn't do.

     Decals hazing causes the decal as a whole to show up - not be painted on, but look like a common sticker!  This makes me positively sick, but there is nothing I can do.  I'm hoping that misting the whole ship will fade it away some.