I looked at their website and didn't really see who pays them. If their fee is the difference between the short sale price and the negotiaited price the buyer pays, then, since the buyer brings the money, the buyer pays. In this instance, the seller would get bupkis.
In effect, they are doing a quick flip.
One of the methods these firms use to to be the contract buyer of the property and then "assign" the contract to a real buyer or ask the seller to amend the contract with a new buyer substituted. Most banks are wary of this because they sit there and wonder, why is a middle man being paid when we're taking a loss.

I agree with your logic. Kwik is acting as the investor who has the cash lined up to make things happen. While I may technically be paying their commission as the buyer, I know what I want to pay for the house. If I can get it for that price or less, then I have to just reside myself with ignorant bliss about what Kwik may have purchased the home for. If they get it for half price, good for them.

While the banks should be scratching their heads about a company like Kwik being involved, they are insured to some extent by the government for their losses so I think in the big picture, they are doing just fine.

Yeah, that's called ultrasonic leak detection. My company actually does this as a service (among hundreds of other things) to check for leaks in compressed air lines in factories. You pressurize the lines and then listen for the "sound" frequencies generated by a slow leak. With burst pipes, it wouldn't work because the lines wouldn't hold any pressure to begin with!

Most plumbers probably just pressurize sections of pipe and then attach a pressure gauge to see if it holds pressure.