Like the grass fed butter that is highly recommended, if I find grass fed cheese, milk, or yogurt, can those be consumed on the diet or do they remain in the "toxic" zone?
I don't think a small amount of raw-unpasteurized whole milk or yogurt will ruin your diet if used on occasion. According to Dave it should be from raw, organic grass fed cows milk, but he recommends avoiding it if you can stand to do it. The reason is because cows milk is an allergen for many, many people and when consumed in the a.m.you are getting sugar which sets you up for failure for the rest of the day. Lactose contains disaccharide sugar and no matter what kind of sugar you have for breakfast it's not a good way to start your day.
On pg 176-177 in 'The Bulletproof Diet book he explains this in greater detail. If you haven't yet purchased his book I highly recommend it. He doesn't just say, Do this. Or Do that. He gives us the science behind his recommendations and explains in simple language. It's my new bible! . Best wishes to you for health.