I'm not sure if the comma before the word "and" is properly used in the sentence below this paragraph. I believe a comma is not needed because the second clause is a subordinate clause, but I am not completely sure. I'm trying to improve my grammar and would appreciate any help or advice. Thank you.
"Your country's moral superiority is a scam, and has been exposed as what it is numerous times".
You don't have a second clause conjoined with "and" to the first. You have a two-part compound predicate:
(is a scam)1 and (has been exposed)2.
Ordinarily, commas do not separate the two parts of a compound, but leaving out the comma will leave you with a problem of style, what Steven Pinker calls a garden path -- a construct that will mislead the reader, who will see
Your country's moral superiority is a scam and ....
and may expect the second part of a two-part compound object:
Your country's moral superiority is (a scam)1 and (an outrage)2....
instead of the second part of a compound verb. Leaving in the comma is one choice. Another is to rephrase to get around the problem:
Your country's moral superiority is a scam that has been exposed for what it is numerous times".
