Grandma knowledge in our areas - whenever someone who is known for their black tongue ( that which comes out true) speaks or blurts out, common salt is taken and circled around the person who is subjected and then thrown into running water, well, sink or drain. The salt is believed to remove the negative effects and bad energy.
Recently, I saw a video where the speaker demonstrated how common salt could be used to neutralize negative energy present in the house. He sprinkled salt, left it for about four hours and vacuumed it away.
Some may think this is all nonsense but since our grandmothers use it, I too believe it.
Who would not want positive energy? So, try it if you feel you need it.
Negative energy spreading examples - suppose someone is angry and vents his anger on things lying around the room like pillows or cushions - then just move about furniture, sprinkle the salt and wash or blow it away.
Also, remember, personal cleanliness is the best way to remove the negative energy and put on fresh clothes so that the new smell rejuvenates you.
Just my humble words