Hotels Combined — affiliate fraud
Hotels Combined get affiliates to sign up, but as soon as they reach the payment threshold, they suspend your account. This has happened many times to many affiliates.
The explanation from Hotels Combined is that the traffic that we send to their hotel partners, doesn't convert. Therefore, they suspend your account, and do not pay out anything. This is most certainly fraud and a scam, and would NOT hold up in court. However, they are smart enough to only do this once you reach US$100 payment threshold.
If you are an affiliate and respect your efforts and time, stay away from Hotels Combined. These guys are either scam artists or complete amateurs, building a business on the back of the hard working men and women who send them traffic and make them money.