In a proper secret-ballot election, it's impossible for anyone to ever tell how a particular person voted unless the election was all but unanimous in a particular precinct (if there were 300 ballots cast in a precinct, 299 of them were for Joe Quimby, and one was for Lionel Hutz, the person who voted for Lionel Hutz would know that each of the other 299 ballots was cast by someone voting for Quimby).
If the ballots are stored, in order, on a paper roll there's no way a voter can be sure people won't discover how he voted. By contrast, if someone drops a card into a box which is large relative to the number of cards such that the card can fall randomly, then (especially if the box is turned over occasionally) it's impossible to associate any particular ballot with any particular voter.
I have never seen anyone wearing gloves to vote. Paper ballots are touched by each voter leaving fingers prints. My polling place is in a privately owned clubhouse where cameras would be easy to hide. Impossible is impossible. The best we can do is highly improbable. As for the Lionel Hutz, Quimby vote. Quimby would get Fat Tony to replace all the paper ballots with his own.