Tar stain no leave my carpet, tried top 20 products, no luck, will try this though:
"If you have a light color carpet and you can't get the stain to come up, then there is a short-term solution that might help, and that's talcum powder. Just sprinkle enough on the carpet to cover the stain. This won't last long, of course, but it might get you through the event without too much embarrassment."
And have some stains which were overdone and carpet got too light as if bleach hit it, will add some watery soil to match and mask.