I have been curing and trading farmer villagers. After one or two trades, their trade values go up absurdly for pumpkins and melons (my main trades). I have not hit them or done anything to suggest why their trades would go up. You can see with the other trades (potato and carrot) that the trades should be lower and that they have been cured once.

As for their "living conditions," they dont have access to a bed, which I didn't think influenced their trades. They also have a zombie nearby to convert them, but not within eye sight.