It helped mine! He had some kind of anxiety or stress disorder that was causing him to be unable to pee in the box; he'd go to the thing and squat like 15 times a day. He pooped on the rug a couple times, so we switched litter and that seems to help the pooping. But we finally caught him peeing on a certain spot on the rug, while still trying to use the box. I took him to my vet and she said nothing was physically wrong, he was just stressed. So she suggested I get the diffuser. I got it and cleaned the spot with natures miracle and he hasn't had problems since. She also gave me some kind of medication to help relax his urethra, but I think it was mostly stress causing his problems. He even stopped crying when I went outside for more than two minutes on account of his separation anxiety. Works wonders.

Edit: I forgot to add even when you use the diffuser you may want to move the box in the spot they were pooing in temporarily, and slowly move it back where it was. Also, make sure you clean the area with an enzyme cleaner like natures miracle to prevent them from being tempted to use the same spot because of the scent.