There are some stubborn and tough stains on the earth which are impossible to vanish. No Carpet cleaning service guarantees a complete stain removal service. Obviously a good method of carpet cleaning results good on the old and rigid stain. However there are some substances on the earth that will permanently discolor carpet fibers. So in that case it is quite difficult to get all the stain eliminated if the carpet has very old urine stains, bleach or some permanent inks or dyes stain.