There was an episode of "Fake Britain" dedicated to this problem. The Chinese are adept at not just copying the anti-counterfeiting features but in keeping up to date with the frequent packaging design changes which genuine manufacturers use to keep them guessing.
When intercepted at Dover, they find bales of tobacco and separate boxes of packaging, for multiple brands, still in 2-D form. These go to a UK-based sweatshop for assembly (complete with obligatory floor-sweepings) and distribution.
Even before I gave up and even though all my rolling baccy was marked 'duty paid' I found them to be incredibly variable in quality. One pack would smell like sultanas and taste sweet, the next would occasionally taste like burnt rubber. At the time, I thought "no way would any consumer show tackle this, cos cigs are non-PC".
The 'generic' tobacco, when lab tested had unacceptable levels of toxic heavy metals, such as cadmium and mercury. The whole reason that Chinese factories are cheap is that they do not bother with the quality control or safety procedures that we have.
If the retailer is visibly struggling (overdue for redecoration etc.) then it's likely that they may be resorting to selling these cheap, fake, products.