I would have them dump their Halloween bounty onto the table.
I would then proceed to search through it for unsealed packaging, foreign substances, or anything looking out of the ordinary. Anything falling into that category went into a separate pile to be discarded.
Any candy that looked spoiled or tainted went into another pile (notice the infected tip on the candy corn above.)
Finally, I would put the Reese’s and Snickers and the others that I really liked in a “For Further Review” pile.