There are many statistical methods to detect irregularities in voting, it would be very detectable if mass organized voter fraud took place.
Vote irregularities happen every democratic election. You have to prove intent and assign blame, with evidence. Irregularities will happen at same kind of rate as other elections.
You can't hold weight in anecdotal stories and pictures without hard evidence. Let's imagine candidate X wanted to have a safety net for losing an election, so they have a pile of pro X votes dumped, to undermine the election.
My point being, finding an irregularity such as a pile of dumped votes does not provide motive or the guilty party.
You can't assume the winner cheated just because they won, it may well have been the loser cheating.
Lastly, check your own bias. Want to call the election a fraud and a full recount whoever wins?.... you sure?