Yes, any color really; anything that reflected more infrared. Man-made fabrics, foliage (brownish greens), faces... Before getting an M8 I had heard about this but in my first few months with it I just didn't see a problem so didn't use the UV/IR Cut filters. Shortly afterward I went on a University trip sans filter to Malta and saw the IR effect in many photos there. I became a believer, and still use the filters on all digital M cameras!