I see this question time and time again, posted on forums, and other places. Well in my opinion there is no set answer. The girls who answer these questions as to what they use and don't use, will it help, well maybe. They will tell you what they like and what it has done or not have done to their faces. Just because girl X can't use a foundation with bismuth oxychloride in it doesn't mean that you can't, or that mica, titanium dioxide so on breaks out girl Y skin, or makes it itch doesn't mean it will do it to you. You have to try it and see if it works for you or not. A lot has to do with the way the products are made and what the company uses and their percentages. Most mineral make up companies use the same ingredients, so why does one work for some and some don't, wish I could give you an answer. When we reformulated our foundation, there were things that didn't work on my skin, I cannot wear a foundation that is heavy on titanium dioxides, I break out, or magnesium stearate in eye shadows, a lot of companies use this and made my eyes itch, so we don't use it in our line but this doesn't mean that it doesn't work for others.
Also take into consideration your skin care, maybe what they are using is reacting to their skin care, there are a lot of things that can make them not work, or not. I couldn't use a foundation that had bismuth in it made me itch and I had a glow to my skin, not pretty. Then I switched to another foundation loved it worked beautifully, come to find out it also had bismuth in it, but I had none of the problems with that one as I did with the other. If I went into it with the fact in my head that all items with bismuth are going to make me itch, I would never have had tried this one. So what I am getting at just because one brand doesn't work doesn't mean another won't so don't limit yourself. Or that this girl said that this is no good for her skin, doesn't mean it will be for yours. This is why most companies offer samples to try out or if you go to a department store and have to get a full size, make sure you check their return policy to see if you can return it if you get a reaction or don't like it. Why be stuck with something you can't use. Have fun sampling and make your own decision as to what is good for you and what you like!