Lots of dodgy pills are mixed in either a blender or cement mixer apparently, so when they dump in the active ingredient there's often hot spots in the mixture.
Happens all the time with dodgy benzos too, but they're much less likely to be deadly than fenty.
Police video shows pills gang in action as they operated Scotland's biggest ever drugs factory that flooded the streets with millions of killer fake Valium tablets.
www.dailyrecord.co.uk
Look at the clip of this place for instance! Imagine trying to have any modicum of quality control with something as strong as fent!