coffee enemas have many other benefits than just raising glutathione levels. Actually, due to its action on the liver, many experience a sense of calm and peace following it, as well as good energy (not a "buzz" like caffeine orally ingested would induce).
About NAC, I had troubles even with pure NAC powder. I found it useful for parasites and liver health, but it made my candida worse in specific circumstances. How am I so sure? Because I tried it following a high enema and it made my candida grow out of control in a matter of minutes. High enemas are beneficial when you're very sick but they also deplete the gut of good bacterias, that keep in check the candida. If you don't follow your enema by a probiotic retention one, you're going for troubles. Same issue with SAM-e.