1.5 year-old tufted off-white nylon broadloom with poly/poly backings stretched over 1/2″ bonded polyurethane pad and concrete slab. Complaint: carpet won’t stay clean. Never cleaned. Spotted with consumer product pH 12. Test cleaned in worst traffic lane: vacuumed, preconditioned, agitated, dwell time, HWE 3x over. Conclusion: trash spotter; have carpet professionally cleaned at least annually – semi-annually even better.