Dude, you're on CRACK!. At idle, ANY car will show the MOST vacuum (compared to any other time)in the intake manifold, and on most healthy motors it's around ~18-20inHg!
Think about it, the motor is running, yet the throttle body is fully closed and the only air it is getting is through tiny hole of the Idle Air Control valve, thus you will have a lower pressure inside the intake manifold as compared to atmospheric pressure, hence you have a VACUUM.
Make sure you know what you're talking about before you spout "wive's-tales" as truths!
