This is one of my least favorite episodes, because Flim and Flam don't seem that bad to me. Their machine works perfectly: it's faster than doing it by hand, and the cider is just as good according to the ponies. They're presented as if they were scam artists, but it's not a scam.
During the contest, Applejack's family is losing. Applejack was wrong about being able to keep up with the machine. Her boast was incorrect, and so they are losing, and so they cheat. They clear it with the judge and even with Flim and Flam, so it's technically allowed, but it's still changing the rules because Applejack is losing.
Flim and Flam lower their ingredient filter to keep up, but we've already seen evidence that they are faster at producing cider which is at least as good. They should have won. They told the truth and did everything they said they'd do. We're expected to hate them because of their personalities, not their actions, which seems like a dubious message.
The apple cider shortage, which has been going on for years now, will remain unsolved. 🤷