From what I've read about this project so far, it requires adding "a single line of JavaScript to the site." So what's to stop scammers and spammers from just blocking the file from loading?
If there has been no JavaScript activity from a user who makes a transaction on your site, that is a fraud signal in its own right. (You can send us events from your server in addition to adding the JS to your site, so that we know characteristics of your users' transactions that can't be gleaned from the JS. In both cases you set the user ID in the call to Sift.)
