Spot test is my favorite tool of analytical chemistry because it is a cheap, efficient and fast method of identification of chemical species. Moreover it is a very instructive field of science because it always gives you the oppportunity to increase your knowledge of our world. For example if you are on the field and find an old mine, you may with no specific tools of analytical chemistry, such as a pocket laboratory, get useful informations about mineral identification :
Sulfate ? heat the powder of mineral mixed with carbon. add o drop of HCl, if you detect the odor of hydrogen sulfide, ... you will deduce the mineral is a sulfate.