How do SiteMeter and StatCounter manage to filter out the referer spam, yet Google cannot do anything about it?This would be quite a magic trick indeed - if this was happening.
That's such a simple way to gather information about your visitors - and for its simplicity, it is unreliable, in various ways.
- Your visitors who use computers that filter content from domains - like BlogSpot, FlagCounter, Sitemeter, StatCounter, or possibly your non BlogSpot custom domain - won't be counted, reliably.
- Your visitors who share a caching proxy server won't be counted.
When Blogger / Google designed the Stats visitor information accessory, they used another technique for counting visitor activity. Blogger, unlike FlagCounter, Sitemeter, and StatCounter, has access to the server activity logs. When Stats was activated, for the Blogger blogosphere, they activated it on a blog by blog basis - and without requiring any updates to the blog code.
Every Blogger blog was given Stats access, and the statistics initially provided preceded actual Stats availability, because nobody had to install any accessory code to the blogs. That is because Blogger uses the actual server activity logs - and does not require add-on accessory code.
Unfortunately, server activity logs only record server activity - and this is how referer spam works - and why it is so hard for Google to block it. Referer spam is simply a normal access request from the spammer, which generates a server access record, and a Stats pageview. The spammer simply goes away after generating the initial access request. The Blogger server, as with any non Blogger server, has no way to detect when the spammer drops the connection and goes away.
Since third party products like FlagCounter, Sitemeter, and StatCounter use add-on code, they are not susceptible to referer spam techniques. Only products which work from the server activity logs are susceptible. FlagCounter, Sitemeter, and StatCounter, and other third party visitor information accessories, have no need to filter bogus activity.
And this is why I have stated that the only way that referer spam will ever go away is for us to make it unprofitable for the spammers, by not clicking on the links in the Stats logs.