To compare the weights of flour scooped from a flour bag and flour spooned into a measuring cup, I used my postal/kitchen scale to weigh each measurement.
First I scooped 1/4 cup of white rice flour directly from the container and weighed it. It weighed in at 1.8 ounces. Next I measured 1/4 cup of the same flour by spooning it into the same measuring cup, cutting the top, scraping off the excess flour with a spatula and weighing it on the same scale. This 1/4 cup of white rice flour weighed in at 1.3 ounces, a difference of .5 ounces- a big difference when it comes to the chemistry of baking!
I conducted this little experiment twice, to verify the weights and produced identical results. Scooping a variety of gluten free flours called for a recipe could, in fact, add several ounces of excess flour and starch to your recipe, causing a less than perfect outcome. Bottom line- spoon, don't scoop!