Here's a quote from audiotubes.com. Hope it helps.
" The Mullard fakes are usually late vintage Brimar made tubes that have been relabeled as early shield logo or BVA logo Mullards. The GENUINE Nasty Old Stuff Telefunken and Mullards usually have some of the label smudged, smeared, missing or blotchy. Very rare are those tubes still sealed in their boxes with even the cellophane wrap intact! These real labels used a chalky flat white paint, never shiny like baked enamel. Just rubbing in the box can wipe off some of the label. RCA and Amperex used the same paint, and not until the late 1970s did both of these companies switch to the shiny orange baked enamel label which was harder to wipe off. RCA used it on their new logo, and Amperex used it on later versions of the world logo. So how do these big time tube dudes come upon dozens of perfect labelled NOS tubes? The secret is: they don't find them any more often than I do! I rarely find perfect label NOS tubes, and when I do I brag it up and down the webpage! These dudes have either unwittingly (or knowingly!) purchased a bunch of these perfect looking fakes---which in this case are truly Nasty Old Stuff---or maybe they should be Nasty New Stuff."
Take your conclusions...

The full article (NOS Tubes: New Old Stock or Nasty Old Stuff?) here:
http://www.audiotubes.com/nos.htm