Alot of stuff...are not detectable via tests.
Most US UGL vendors are using bottletop filers, which contain polystyrene, which leeches under BA/BB. With the volume Q sold, it's definitely not bottletop. Either way, I melted a Corning Bottle-top filter in BB today, hopefully Jano can come out for a test for it. My BB looks completely clear even after the plastic is gone.
Q also sold alot of guaiacol free oils, which US Dom vendors used guaiacol for (injectable orals). It's only recently did some new vendors start introducing g-free versions. If you look around, all the old vendors are still using g for it.
It's the same as silicone, etc, even if it's your oils..you don't know..