To NAC, or not to NAC?

Once again I notice someone comment on their Pulmonologist recommending NAC. My Pulmonologist (reasonably young, good standing, up-to-date) insists it is a complete waste of time. This is essentially rather strong coming from him as he normally goes along with most alternative supplements - "May help, so what's the harm".
I tried it once, stunk so bad I couldn't bring myself to try again. <smile>