Link-Only or Spam?
Two cases come to mind:
- A new member registers and posts a link-only answer
- A known member posts a link-only answer
We've had both cases on TSE. So here are a few examples.
1. New Dog Old Tricks
If a newly registered user posts one or more link-only answers then it's easy to suspect that their intent is to spam a product/company. However we as community members cannot blindly be judge, jury and executioner. There is one case in which one should arguably give the benefit of the doubt, and that is when the post is a quality post aimed at answering the question. However one should always check for missing disclosure of affiliations, and comment and flag accordingly. The way I usually go about it is that I downvote and ask the user to disclose their affiliations. If I get no response in the following 24-48h I go back to the post and flag it as spam. Remember that undisclosed affiliations count as spam, according to SE regulations.
The other case is when the answer looks something like this:
Oh yeah I hate when that happens but now I use ThisSpammyCompany and my problems are gone.
Although this might indeed answer the question, since ThisSpammyCompany could effectively be running the best service out there, the user just wants to spam them. I see no quality contribution in these posts. My method for dealing with these is to downvote and flag as spam. The reason for the extra downvote is for the post to reach the Low Quality Post queue and filters as quickly as possible.
2. Old Dog New Tricks
In this question on flight searches to Anywhere, @chx answered with a link-only post. That post was flagged for deletion, IMHO correctly so.
The community could have questioned the intent of @chx, and someone should have added a comment asking them to disclose their affiliation. However being a known community member, nobody suspected spam on his side. Instead the community questioned the usefulness of an answer that basically said RTFM. The result: it was flagged, discussed on meta, improved and fixed.
All in all I would stick with the SE regulations on spam:
Avoid overt self-promotion.
The community tends to vote down overt self-promotion and flag it as spam. Post good, relevant answers, and if some (but not all) happen to be about your product or website, that’s okay. However, you must disclose your affiliation in your answers.
If a large percentage of your posts include a mention of your product or website, you're probably here for the wrong reasons. Our advertising rates are quite reasonable; contact our ad sales team for details. We also offer free community promotion ads for open source projects and non-profit organizations.
For more information see my other answer on the topic.