As a matter of fact, it is normal for patent examiners to not even read the invention specification and focus only on the claims.

I was surprised to learn that from a patent attorney, but it seems to be common knowledge, e.g. [1]. Upon reflection, that's the only way it can work. A generalist patent examiner could never understand all the inventions given the volume of applications they must handle.

[1] http://www.ipwatchdog.com/2016/07/25/anatomy-bogus-alice-rej...