What's the rule when you've got two adjectives in front of a noun, and you have to decide whether to stick a comma between the adjectives?
It comes down to this:
1. IF [coordinate adjectives], THEN [comma]
2. IF [non-coordinate adjectives], THEN [no comma]
A pair of adjectives can be called "coordinate adjectives" if (1) their order can be reversed without damage to the logicality of the overall expression, or (2) if the word "and" can be inserted between them without damage to the logicality of the overall expression.
So which of the following is correct?
(a) the big angry man
(b) the big, angry man
Do the test:
1. Is "the angry big man" still conveying the same idea?
2. Is "the big and angry man" still conveying the same idea?
If yes, then insert a comma.
Correct answer: the big, angry man.
Look at the following example, pulled from a recent article about a Korean singer accused of beating his girlfriend, a certain Miss Choi:
Unfortunately, many of Kim Hyun-joong’s young fans seemed delusional in their unwavering support of him, instead bombarding Miss Choi with malicious, personal attacks.
My focus here is on the comma between "malicious" and "personal." Should it be there?
Do the test:
1. Is "the personal malicious attack" conveying the same idea?
2. Is "the malicious and personal attack" conveying the same idea?
I'd say the answer is yes. So the comma stays.
Mignon Fogarty, a.k.a. Grammar Girl, offers the phrase "exquisite custom houseboat" as an example of when not to use a comma between adjectives. She identifies this pair of adjectives as cumulative (i.e., non-coordinate): they stack on each other only in a certain way, and their order can't be reversed. Ergo: no comma. You can't say "a custom exquisite houseboat," nor can you say "an exquisite and custom houseboat" without messing with the phrase's logic because, as Fogarty points out, "exquisite" is modifying not just "houseboat," but the concept of a "custom houseboat."
And since there's no need to multiply entities beyond necessity, I'll leave off here.