Re: A question about foundation
AW - it probably does, you just haven't noticed it yet.
To be honest, I used Studio Fix Fluid NC30 for two years without problems - never looked darker in real life and in pics looked lighter, if anything. But I did apply it sparingly. One day I looked in the car mirror (LOTS of natural sunlight) and saw faint orange streaks. No one else could tell (went around asking everyone that day) but I knew and it bothered me enough to change foundation.
If someone applies it a lot more heavily for more coverage, I'm sure it would end up making them look darker after a few hours. ALSO, it depends how your skin reacts with the foundation, some skin types will affect it more than others.