Caution: You are about to learn how to clean greasy range shakers with ease. This method works only on glass range shakers where the glass is itself is colored, not fired-on like vintage Pyrex bowls. Never use this method on pottery or fired-on / painted-on vintage glass (such as the Jadite shakers shown below), including lettering, stripes or dots found on Depression Era kitchenware..
Oh, how we love vintage kitchenware from the 1930s-50s . . . it's useful, comes in happy colors and reminds us that in the not-so-distant-past all food-stuffs were prepared from scratch!
Vintage glass range and spice shakers are often found with what appears, after washing them several times in hot soapy water, to be permanent stains . . . irremovable little spots and icky gunk in the grooves that simply won't wash off.
Here's an RSS, a really simple solution . . . spray a tad, just a tad, of oven cleaner on them, scrub a little with a brush or scouring pad and voila' the spots and gunk are gone. Wash, rinse, repeat if you didn't get it all.
Use caution around stripes, lettering, dots, tulips et al . . . these are not part of the glass, they are painted on or fired-on and won't hold up to the caustic nature of oven cleaner.