I just opened a 4956 (Creator/house) set I've bought (in Oslo), and immediately noticed that some of the parts were of seemingly cheaper quality. Their shape seem ok, but the color is more "milky" translucent rather than solid.
It's most prominent for the white bricks, almost all of these are of the "cheap" kind except 1x2x1, 1x16x1, 2x2x1, 2x8x1, 1x4x1/3 and1x6x1/3. There were 1x8x1 and 1x2x5 of BOTH the regular and the cheap kind, unfortunately I didn't check if they came in different bags.
Most of the grey parts are of the regular kind, but 1x2 and 4x6 plates and 1x1 and 1x4 tiles are of the cheap kind. I'm not sure if it's just the color or also the plastic, they seem to have *slightly* more grip than the regular ones. I just tested some of the white 1x8x1s, what's odd is that most of then have the modern hollow underside pegs, while one regular AND one cheap one have the old solid pegs. If I take a handfull of the regular and a handfull of the cheap ones and rattle them, I believe the regular ones make a slightly deeper sound.
This set is marked with "made in DENMARK, AUSTRIA and the CZECH REPUBLIC", I really suspect it's the last of these which is the problem. Does this mean that the outsourcing plan has turned out just as we feared it would turn out? Or is it just a minor issue with the new "in-mold" coloring process they talked about?
BTW, these aren't the first translucent parts I've seen (but never at this scale), I bought 4896 (black car) last summer, and noted that the grey 1x2x1 L-panels were of similar different translucence.