that's a risk you have to take, at some point. you eventually have to trust that someone isn't lying, somewhere along the chain.

what else could be done to further vet volunteers? you can't interrogate people or drug them with serums for the truth, so I think it's safe to assume registering is enough.

so, to answer your question, I doubt there is any "guarantee" other than the fact that these are volunteers and you'd have to be a real idiot to falsely register to ensure you can tilt the scales...of bipartisan pairs of Arapahoe County poll volunteers.