I just read that vinegar mucks up ph of the carpet and if you don't rinse it very thoroughly you will have created a spot where colour will fade and more dirt will be attracted in.
Ie you will have made it all worse...?!
I have a big stain on my bedroom carpet, it was a mug if coffee. Have tried al the usual products, and, incredibly, it's still there, faded, but very much still there.
Getting desperate and have the vinegar at the ready...