When creating adsense ads, I usually tend to omit the part which allows you to display an alternate ad url in case adsense cannot find any adverts to display in its inventory. This can be a costly mistake if your website is showing Public Service Ads (PSA) quite a lot.
The options that you have in adsense is to have a solid colour instead of the google ads if not matching ads can be found or have a collapsing ad unit or supply an alternate ad to display. The solid colour can be used to match your background but the problem is that it will be an empty space which is not going to earn you any money and look rather odd from the layout point of view. The collapsing ad unit is quite clever although there’s a bit of setup to be done and although it’s not going to have blank space, it will nevertheless hurt your earnings. Supplying an alternate url for another advert is the best choice – you can have your own banners to promote your own services/products or have other banners through affiliates which can earn you some money rather than nothing.
I opted to supply my own alternate ad url and decided to log the number of times PSA ads were showing on my website. This would help me understand how much this is impacting my revenue but I also wanted to know which pages were serving these nasty PSA ads as well. So I coded the alternate ad url so that it recorded each time a PSA was shown on my site as well as the page which was showing the PSA. Within 12hrs, I’ve already got 6 PSAs and all of them were coming from the same page. I guess the problem is that no matching ads could be found for that particular page because of the content (text copy) so I probably need to rework the keywords for that page.
I’m quite happy though that I implemented this solution because now I can see where PSA ads are being displayed as well as how many times they are appearing and on top of that, I’m not losing out because an alternate ad is being shown instead of the PSA!