Spiritual hygiene didn't matter at all in the really messed up situation I was in with a Jew (who I didn't even realize was one at the time) about 6 years ago. I got pretty much taken out for 3 years straight and even ended up on enemy side for a bit with angel Magick cause of the entities and energies that were attached to said jew then me.
People have to be really careful to be aware of who they are around. But yeah it can be countered as long as one is aware and doesn't let the energy build up or parasites attach too deeply.