What do you mean by unfair bets? Is it something if anyone win the bets then you will called it unfair or there is something difference? And you will not give refund as the user is already in profit but will you give refund to those users who is in lose? Would you like to explain it clearly?
Winning is not a violation on 1xBit. But winning via various schemes like arbitrage is.
If you just play at 1xBit, without intentions to circumvent the ToS (which you are agreeing to by placing bets) - there won't be troubles.
How do you investigate arbitrages? As far as I know people bet on different sportsbooks according to their odds to win any way despite the result or does arbitrage betting include the combination of prematch and live bets? (In live odds change frequently and significantly).
And about the scams, you should avoid situations like this, users mustn't have a need to create thread here and get refund after that.
Check this post of your:
https://bitcointalk.org/index.php?topic=5336412.msg57563229#msg57563229