PCV Valves are open at idle. One set of ring seal is to idle the engine, pull the breather and see if a piece of paper will get sucked down in the open hole by vacuum (obviously you have the PCV in place for this test).

If it doesn't get pulled down and seal the hole, or worse yet you see exhaust pulsing out the hole you have ring seal issues.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.