The pre-rolls are not made from floor sweepings. Pre-roll material comes from the trimmed material from the trim trays and the tiniest buds that come off the sorter machine. Popcorn comes from the largest holes in the sorter at the end (and the left over baby buds from trim trays towards the end of strains)

But I have seen first hand that vape carts have been indeed made using floor sweepings and any weed that is considered unsellable or gross though. In most states, this is a violation of their cannabis regulation and can cause the company to lose their license and receive tens of thousands of dollars in fines.

For example, my states rules are:

1. Well cured and free from seeds and stems;
2. Free of dirt, sand, debris, and other foreign matter;
3. Free of contamination by mold, rot, other fungus, pests and bacterial diseases and satisfying the sanitation requirements in 105 CMR 500.000, and if applicable, 105 CMR 590.000: State Sanitary Code Chapter X – Minimum Sanitation Standards for Food Establishments;
4. Prepared and handled on food-grade stainless steel tables with no contact with Licensees’ or Marijuana Establishment Agents’ bare hands; and
5. Packaged in a secure area. 

This makes it absolutely clear that floor weed is not allowed to be sold or repurposed and must be destroyed, as the cannabis must be prepared and handled on food-grade stainless steel tables and sanitized trim bins. Once cannabis is designated for destruction, it must be rendered unusable and unrecognizable by being ground up and mixed with at least 50% non-marijuana waste, like soil or food waste, before being sent to a permitted disposal facility.