I’ve hired a musician to record a few parts, and I believe the preview they sent me was available for me to download as a wave file before I even approved it. That means I could download the full quality audio and never even pay them. Other sites keep previewed audio in lower-quality mp3s, and don’t make high-quality .wavs downloadable until the buyer has accepted the product, and therefore requires payment to be released prior to having access to the full product. Someone wouldn’t even need to download the files to rip off the seller; they could simply record it through the stereo mix in their computer and have a high-quality recording, and then disapprove the job, saying they aren’t satisfied with the work or whatever, and the seller wouldn’t even know they’ve been stolen from.
Actually, I have to amend this. The .wav I was able to download was one the musician uploaded to our private chat, not the chat for the job itself. When the work was delivered, it could not actually be previewed as a .wav. And they were careful by only uploading their recording over top of the backing music. But it might still be safer to automatically downgrade .wavs no matter what chat they are uploaded to.