Everything in the world is made out of energy. Our belongings all have their own energy fields, just as our bodies do. And even within the body, each organ has its own energy field. Everything has energy.
So sometimes we get objects that just have bad energy to them. You would recognize this as "bad vibes," or just a feeling that something is off. If this feeling is consistent, your object may be carrying some residual bad vibes from its past. Many people don't realize that used items--and even new items--can come previously infected with negative energy.
The easiest way to remove negative energy from something is to pray in faith for the negative energy to be neutralized or removed. The trick to effective prayer is visualization: ask for the negative energy to go, but then visualize or imagine it going. If you can't imagine it going, then just imagine what it would feel like to imagine it going. That can be good enough!
You can muscle test on if you own any items that need associated negative energy cleared. Your subconscious will know the answer to that. And you can muscle test after you pray for the clearing, to be sure it went through.
Other ways to clear things of negative energy are to sprinkle it with baking soda, sea salt or Himalayan salt or other natural salt, sage smudge it or use sage essential oil on it and the area around it, or leave it out in moonlight. Or bury it in a good patch of earth. But using prayer and intention is the easiest way.
Items and objects can carry negative energy. Your subconscious mind recognizes this subtle energy and can respond accurately to its presence through muscle testing. Prayer with visualization can be an effective way to clear negative energy from an object or a space.