Usually (assuming the posts are disclosed, relevant to the site/question, and it's 100% of the user's posts), if the product is the answer (eg. "you can use my library to solve this: .. [writes about how to use said library]"), 3 is overly promotional to me. If the posts have actual purpose other than to promote something (eg. "[Full answer to question] ... I wrote more about this in my blog:"), then 5 is overly promotional to me.
For software recs, I usually bump the first category to 4 posts.