It looks like only site owners proxies are winning those lotteries because so far no has claimed that they won the lottery from that site. So don't buy any lotteries from them and if you want just use their faucet and buy lotteries from some other sites. No one knows on what basis they pick lottery winners.
I have won there once, but only 0.00021490 BTC.
But it was from the Lucky Number Roll, not from the Lottery game. Anyway, it was a nice extra satoshi amount, because it helped me to reach the withdrawal limit. Nowadays it takes weeks to reach it, because the earnings from the faucet are reeeally small.
The multiplier is provably fair with a low house edge, but the faucet income is determined by the Bitcoin price. The higher the Bitcoin price, the
lower is the amount being paid out by the faucet. The amount being paid out by the faucet also seem to be location based. In countries with
stronger currencies, the faucet pay out seems to be higher. { I think that is to make it more viable for people in these areas to use the
faucet} I stand to be corrected.. or it might have been because advertisers valued traffic from these areas more.