Google Adsense Tutorial, How to filter unwanted Ads?

Google Adsense Tutorial
How to filter unwanted Ads?

Geting rid of unwanted Ads is an important technique in maximising the profits from Adsense. Adsense sometimes serve ads that may not work very well towards maximising the profitability of valuble online virtual real estate (i.e the Ad space on a publishers website). Some of the examples are PSAs (Public service Ads), untragetted Ads, Ads of the competitors etc. A publisher has to avoid these things as much as he/she can using proper content optimization or by using the filtering facility.

Google provides tools in Adsense account such as Competitive Ad filter. With the Competitive Ad Filter, a publisher can choose to block ads that link to specific URLs. The filter prevents all ads from the specified URL from appearing on the publishers web pages. Up to 200 URLs can be filtered like this. While it is good idea to prevent unwanted URLs from apprearing on a website, it is possible that webmasters (i.e publishers, website owner, blog owners etc) may use it a little too much, which can even hurt them. So let us see how and when and to what extent to use this tool.
When and How to use the Filtering Tool?

Now let us consider first of all, 'what Ads are really unwanted?' - There are varous types.

PSAs:

Public service Ads are displayed usually when Google has not yet crawed a web page. To avoid these a publisher can choose to display ads from an alternate URL or just a solid color. These option are provided in the Adsense Setup area.

Competitor's Ads:

If a publisher sells services or products through his site, this tool is very useful, as the publisher can avoid direct competitors from advertising on his site.

To block their URLs, a publisher can find them by searching on a search engine for keywords and keyphrases that are relevant for his business and then look at the AdWords that appear. Then chose these URLs to filter using filtering tool.

Untargeted ads:

Sometimes Adsense serves inappropriate ads that are not targeted to the content under question. Most of the times this has a lot to do with page theming and keyword optimization. It is not enough just to filtering them out, but a publisher should work more at page optimization and make sure that the webpage is clearly themed, so that Google can find appropriate and targeted ads that have a greated chance of producing a click.

Some things to consider:

A publisher may think it would be a good idea blocking ads that he considers paying too low or being slightly off-themed. This however, is not always the case. As Google serves most relevant and highest paying ads first, filtering too many URLs may actually reduce the 'earning per click' (EPC) on page and also the click-through rate (CTR). Also, one has to keep in mind that by entering a top level domain into the filter list, all ads that link to subdirectories below that domain will be blocked. This filtering system, unfortunatly, has its own limitations - : it's not just ads-related, it blocks all the ads (not just the unwanted ones) from a URL.

So,a publisher has to be careful not to do it more than required. A publisher usually finds it more profitable to use the filter for what it was intended: to block competitors' ads or ads and URLs that are really of no benefit.