Permanent Carpet Damage

There are certain things that are done to carpeting which becomes permanent damage.

The list is endless, however, bleach is a no no.  Also, mixing chemical spot removers and not rinsing can be bad news.
Another big one is using colored cloths  to rub the spot.  Color dye transfer can occur.
Over wetting and hard scrubbing may damage the carpet.

Call a professional first, not second.