According to an article at DigiTimes, there are a growing number of Taiwanese manufacturers passing off their 8x and 4x DVD+R/-R discs as being rated at 16x or 8x.
Among makers of optical discs in Taiwan, only CMC Magnetics, Ritek, Prodisc Technology, Daxon Technology and Lead Data are currently capable of producing 16x DVD+R/-R discs, while second-tier and smaller makers produce 4x and/or 8x discs, the sources indicated.

As demand for 16x DVD+R/-R discs grows with the increasing use of 16x and 18x DVD burners, some makers have mislabeled their discs with higher speeds in order to grab profits, the sources pointed out, noting that there have been reported cases of counterfeited TDK 8x and 16x DVD+R/-R discs made by small makers in Taiwan.
If you'd like to read more, head on over to DigiTimes.