Though still not a sure thing, this is why I have the wide spectrum of testing products so I can relax max, (Mecke, Mandelin, Marquis). Monday QBing is something I like to avoid, others are more resilient/intrepid...lol. If I know the guy & even supposed batch/substance, I still test for what I can, (& to see sight timing variations)... reaction times can on some things help reveal the cut but of course, not all & not always.