I've been promoting for a week now using text ad exchanges and have no sales. Has anyone had success using this type of advertising? Thanks
Yes, You can be successful by using text ad exchanges. It will be better to upgrade to paid account otherwise be ready to work hard. Safelists also fall in the same category.
Text ads on high traffic site can divert some good traffic from that site. If your text ad is a do-follow link on a good quality, high PR page, then it will benefit you in your rankings and if you maintain the quality of the page, then you can get a high PR for that page as well.
Text ads and traffic exchanges can work well, but you need to know how to use them. Send the traffic to a one-page splash page or squeeze page instead of a sales page. I've found that these types of sites, as well as safelists, are great to prooduce leads for my mailing list, but not too good for making straight sales conversions.