Maybe it's the stuff in the carpet cleaner? If you're cleaning every two weeks or so there could be something in it that tastes good! (Could also be dangerous to furbabies). I
Rugs are not that unusual - since they have edges that are fun :) I have to keep an eye on mine with the rugs.
We don't have carpet so Baron chews the linoleum right in front of me. Bitter apple is an appetizer. The vet suggested hot pepper...Baron went yummy! I need to wear him out with exercise for him not to chew. Baron is now 16 months old and still chewing away. Good luck.