Ive used it for years. The guy i worked for used it everyday. Never any problems. Breathing it straight out of the container i wouldnt advise. But i wouldnt advise breathing in dry hot chocolate mix niether for that matter. I still use formula 90. Only now the liquid version. Theres no lingering odor with either. You can faintly smell it while in use. Once dry the odor is gone. They must of used something else added deoderizer? If at all anything if mixed heavy it will leave carpet stiff to the touch. As far as the sofa idk why he used it there. Acid would be better as rinse to remove and neutralize the pre applied stronger cleaner.