Hey, On a new site I have, most of the posts get regular adsense ads. On 2 posts, it is only showing public service ads. I don't understand this. All of the posts are very related to the site's niche. It is a very large niche, and there are hundreds of advertisers targeting it. Why does adsense sometimes show PSA's? What's the general rule here? Thanks!!
PSA normally shown by google when you content of the article is either not allowed like child abuse, adult content or racist content and it many happen that google don't have related ads with your content.
if you have a niche where there are not many advertisers, then PSA will show when there is no ads to be served. if you dont want PSA, then you can put an alternate ad that will display when there is no paid ads. you can set that up under adsense setup when you generate your adsense code
PSA ads are shown when Google can't figure out what your content is about, when it has no ad inventory for the related content, or when you have overused stop words such as murder, kill, sucide, or other objectionable words. There's a list of the words somewhere on the web, but I don't remember where. Look up "Google stop words"