We become disappointed whenever we receive Google’s monthly Snapshots, and suspect that the large majority of website developers feel the same way. In December 2017 our server statistics showed nearly 100 times as many visitors as Google Analytics did, and in January 2018 they showed 60 times as many visitors as Google Analytics did.
There are a lot of reasons why the Google Analytics figures can be inaccurate, including unbiased ones and biased ones.
Beyond disappointing we become angry when Google wants us to buy AdWords, implying that our visitor counts will be boosted.