Traffic exchange users are comparatively low quality, but they’re still real humans. You’re getting real people to view your site, you’re just not bringing them in organically the way Google intends. You can make money from these users, but your conversion rate will be typically lower than what you might see from organic traffic. Of course, it’s also much cheaper and faster to find this traffic than it is to invest in SEO and content marketing.
Monster-Traffic is another traffic exchange, though it’s initially a little off-putting due to the 1995-style website. It’s a free for all styled advertising list, where anyone signing up becomes part of the audience and an advertiser at the same time. You sign up and you can enter a link into their system, and that link is added to a roster that is send out to every member of the group. Additionally, registration allows a free solo ad; an ad that isn’t drowned out by other advertisers in that mailer.