While we all know that there are no earnings from clicks on PSAs, some people seem to think that the clicks show up on their reports thereby diluting their eCPM. I have always assumed that these clicks did not show up but I searched the AdSense Help Center and could not find it addressed, so I emailed AdSense Customer Support and asked.
They have confirmed that clicks on PSAs are not reported. Pages with only a PSA do not count toward page impressions and if you go a full day with only PSAs and no paying ads, your reports will not show any data for that day.