I`m getting a lot of comments on one of the sites I monitor. It`s a small business site with a blog. The comments are all coherent, well phrased English, and relevant to the topic. However ALL of them have URL`s that are related to the blog`s niche. (For example... let`s say it`s a website/blog about plumbing. So all the commenters list their website as some plumbing company - always out of the original site`s service area - in the URL field when signing up to comment. Many of them leave legit emails as well, because their Gravitars show up.
I`m currently using the standard WP commenting system, which asks for a name, email and optional URL. Any of the comments that are blatant and damaging spam are dealt with by either a spam plugin or manually (by me).
So it`s pretty obvious the commenters are using the comment section on the site I`m monitoring to build links back to their website(s).
What do you do when this happens to your website? I`m not sure of the etiquette or best-practices for how to handle this. From an outsider`s perspective, the comments don`t look bad... but I`m second-guessing what I should be doing with these comments.