I mean from your landing page, linking directly to a sales page, or any page on the site besides the homepage, or even the clickbank cart, and earning commissions that way. Is it possible? I've seen some ads up that do it, but when you click the links it doesn't look like an affiliate link when you look at the navigation bar.
Another possibility is that they are linking straight to the product domain but somehow showing their own domain on the navigation when you click. How do they do that?
You have to check with your vendor first, if you can use direct buy link, format looks like itemnumber.affiliateid_vendorid.pay.clickbank.net this way you can retain the affiliate id in cookies. Also you have to mask your url in order to make your domain name appear in the address bar instead of an affiliate link. Hope this helps