Taco meat is a type of meat, it's not the same as delicious meat (which just tells you additional information about the meat). So basically, just consider taco meat to be the same thing as mobile phone or profile picture (almost a single word), and the comma is needed only if you are using more than one adjective that gives you a characteristic of the thing you are talking about (for example "a cheap, powerful device" or "a brave, admirable man") "They serve cheap and delicious meat." is correct. Hope this clears it up for you!

They serve cheap, delicious meat. One noun : meat. Two adjectives, separated by a comma They always have cheap taco meat. One noun : taco meat One adjective. No comma You could replace the comma with 'and', or - better still - 'but', as the two adjectives contradict each other. 'Cheap and nasty meat' or 'Cheap but delicious meat'.

taco is a noun, but delicious is another adjective so you need a comma. Only use 'and' once - at the end: A and B / A, B and C / A, B, C and D. :)