How do I know my PCV valve is bad on my 1997 Honda crv?

Remove and shake it, if it rattles or you can feel movement inside generally they are ok. they only become a problem if they get gummed up so does not permit movement, possible after many miles. Otherwise, they are pretty indestructible. Some have springs some don't which allow to close more slowly To test since they are pretty much one way valves which close on occasion with vacuum, just wipe off and suck on each side. One way will be no resistance and the other should close off completely so no air goes through