I don't remember ever seeing a healthy anemones(larger species, excepts E.qua) expels brown "poop". An unhealthy/stressed anemone is the ones that expel their zooxa. In H.mag, E.qua, and carpets, their waste have always been with"substance", not just mucus, and never brown slimy for me. In the case of food intolerance, the food will be coated with clear digestive enzyme when expelled. I have seen some newly arrived anemones with mild case of expelling zooxa without deflation and the chance of survival is pretty good if the waste is accompanied by some solid substance , slowly over a day or two the brown slimy waste is replaced with regular waste. In my view, the anemone is compensating and it is on its way to recovery. In a decompensated state, the brown slimy waste is accompanied by frequent inflation and deflation and its chance of survival is minimal. This is more often seen in the Stichoductyla genus(more often with gigantea, red pink "super species" carpets and to the lesser degree in haddoni) and some times, I also noticed in H.magnificas. But, in a magnifica, it has better recovering record for me.
Hope this is what you are looking for Jim, I'll have to look for the pictures I took over the years. Cheers!