That just sounds funny...at least to this yankee.
Burned valves or sticking valves is another thing that a vac guage can reveal, along with exhaust restrictions.
Basicly it is something else to distract you from the road...kinda like your first tachometer.
How many of us had fun watching the needle jump and drop on our first tachs?
Heck, I found the gas guage distracting when i first fixed it...was trying to see if i could actually watch it drop when I hammered it.