I recently had the misfortune of seeing a sign outside a chicken franchise that read hot, juicy, chicken. You can imagine my outrage!!! It, of course, took us here at Language Lady to Comma Clues #2: Use Commas to Separate Two or More Describers (But Not Between the Describer and the Word Being Described!).
I was thrilled to find the image above to instruct you in the commas-with-describers rule because those two benchmarks are the ones that I teach in my grammar books:
1. If you can reverse the order of the words that you are placing a comma between, and the phrase still makes sense, use a comma:
a. She had on that bright, beautiful dress. (She had on that beautiful, bright dress—YES…comma is needed.)
b. She had on that, bright dress. (She had on bright that dress–NO…comma is not needed.)
2. If you can put an AND in between the two words you are placing a comma between, and the phrase still makes sense, use a comma:
a. She had on that bright, beautiful dress. (She had on that bright and beautiful dress—YES…comma is needed.)
b. She on that, bright dress. (She had on that and bright dress—NO…comma is not needed.)
For those who like technical explanations, we teach that commas go between DESCRIPTIVE adjectivest (bright, beautiful) but not between CLARIFYING adjectives (that, five, this–which are usually called something else anyway, like pronouns, etc.).
More on comma before the and in a series of three or more (bright, beautiful, and colorful dress) in Comma Clues #3! Have a lovely, grammatically-correct day!