How to avoid Google Adsense Public Service Ads?
Ensure that META tags like ‘title’ & ‘description’ and the headings tags like h1, h2 etc. have content which matches the rest of your site. They are main ways google judges your pages content.
Add specific keywords in your text which will help the google bot to determine and understand the content of your website. Repeat related keywords which will better help to understand site content. Do not fill your page with similar keywords, it might work against your favour.
Develop sufficient good content with keywords on your webpage related to the topic of interest. Google is a great fan of good content websites.
Try to keep the entire website focussed on a particular theme, so that even if the content on a particular page is lesser, the ads wil show.
Do not place multiple ad units if there are not sufficient ads to display on all of them. Also Google TOS do not allow placing more than 3 ad units on a page.
Use section targeting - you can target an ad unit to a specific section of your blog, as well as block out irrelevant sections like navigational links. Useful to get more targeted ads.