I think that book's been mentioned, but this is the first time I've heard something negative about MSM. My only caution about it is if you are in healing mode, like candida people, you want to use MSM sparingly because it's on the acid side of the PH balance issue, and most of us need more alkaline substances.
It is difficult to know what to take and waht not to take! I think a good common-sense down to earth route is to not believe in wonder drug/supplement cure-alls but believe in the intelligence of the human body. Most of the time all it needs is for us to STOP abusing it and get out of its way and it's fine. Then a good diet of mostly veggies and whole grains, plus little bit of supplementing to make up for our lousy diets will not go amiss either. ;) It also helps to know the signs of good digestion/poor digestion, as poor digestion creates toxins and mess for our bodies that leads to degenerative diseases. Just eating in such a way that our tongues aren't coated all the time is a great thing to do! :)