Here's a handy guide for useful idiots regarding the up coming election day(s) and things that might happen that could result in skepticism about the outcome.
If these happen in swing states then the distrust factor is only magnified.
Voting machine malfunctions, running out of ballots etc. that seem to happen primarily in either highly red or blue precincts.
Ejecting poll watchers of a particular party.
Exorbitant wait times, again especially when happening only in highly partisan precincts.
Stopping the vote count in multiple swing states.
Resuming the count at 3 am, instead of 9 am as promised, in many of those areas that stopped counting the night before.
Phantom water main breaks in key precincts as a reason to pause counting.
Call me crazy, but these are just a few examples of things that undermine trust in election outcomes.