This is my take on it, but other moderators will likely have differing opinions; Only substantial posts should contain a advertisement. There is a difference of linking to a source, and linking to an advertisement. If the user owns the site then its far more likely to be an advertisement, and not a genuine source. However, this should be determined on a case by case basis, and factors that would contribute to determining whether this is okay or not is by quality of their content within the post on the forum, and how often they link to this resource. As linking semi regular would indicate that they're the owner of the website, and they are merely posting to advertisement, although if its a substantial thread then this may still be allowed. It entirely depends on the individual case that we are presented with.
For example, Sally posts a link to a website which contains referral links, but is not a direct referral link, and does not continue to do this multiple times, and is a one off. I would consider this fine as long as its relevant to the discussion, and they offer insightful information within the contents of their post and aren't just linking to a source. At this point, it doesn't matter to me whether they own the site or not. If its useful, and isn't a direct referral link then its fine. However, it needs to be a
substantial post for this to apply. To give you an example of my example; If someone posts within the service discussion section asking for reviews of the top exchanges. A user gives their own constructive opinion on it, and then links to another source which provides reviews from another source on the internet, which happens to have indirect referral links. Using my discretion I'd probably allow this if first of all the post itself was substantial, and it wasn't a direct referral.
However, I believe this should change as soon as this is a regular occurrence of a user, and they're offering low quality posts while plugging a certain website every chance they get. I treat linking to news articles the same, as a lot of users are now trying to get traffic to their website without posting on the forum for discussion. They simply quote a small bit of the article, link to it, and then never return to the discussion, and start the process all over again for their next article. I usually remove these types of threads, especially if there's alternative discussion on the forum already.
Although, this will be entirely at the discretion of the moderator handling the report as we all have different interpretations of post quality, and determining a users intentions when posting a link.
However, if you are using the forum as a publishing platform to host something really substantial and useful, selling ads in that substantial work is allowed. To be eligible for this, your post must be in a topic that you started, and your post must be substantial and long enough to make the ad seem entirely insignificant. If in doubt, ask me.
Before I proceed with my explanation, my personal interpretation from this quote is that theymos is talking specifically about threads that the user created themselves that contain advertisements.
This is the policy that I try to abide by when it comes to these types of posts. Note that, theymos talks about hosting content on the forum which requires the post itself on the forum to be significant, and substantial. However, I'll admit that indirect referral links can sometimes be tricky. If a user replies to another user trying to help them, and links to a resource which includes a referral link within the page then it should probably be removed. However, if they have posted a significant thread of their own, then it should probably be taken on a case by case basis.
