"You don't salute the person, you salute the rank": Do you believe in this age old saying?

I saluted officers from the day I trained in basic until the day I left the Service,so I guess yes would be the appropriate answer,Sir.

Always salute the uniform. That said, consider: For a week in 1975, I was a student at SERE school. We had no ranks. Nobody knew who were the officers or enlisted. Only the most senior officer and the most senior enlisted were known to us. There were no badges or ranks and no saluting. We turned out to be a perfectly good working group during that week. Leaders emerged naturally.

Absolutely. This holds true with enlisted pay grades as well (not so much saluting, but respecting the pay grade ). I have known some clueless officers and have had some horrible enlisted leadership in my day, but you must always respect the rank - even if it includes biting your tongue clean off. To me, even if I was an E9 or a CWO5 and a dumbass new O1 put me on blast in front of our junior personnel, though that O1 will never forget their mistake - I would still render a salute because that's what I am required to do. I hold very tightly to customs, courtesies, and traditions. Though, an O1 must be out of their mind if they step on the toes of anyone E7 and above - at least in the Navy.

There were several Officers I just saluted their rank. there were many more that I saluted them as leaders who earned respect of their Marines.

Mostly true however there are some I'd salute regardless of rank

Nope, you have to salute the rank per regs, doesn't really matter behind that TBH

Military etiquette requires the Salute. It does NOT matter what you think of the person in uniform (great leader or death defying lunatic).

Respect the rank always; respect the service and nation second to none, but; the individual is not important, because we are taught selfless service.

Yes, the rank by standards has to be saluted.
But in my book I've always went by the saying real respect is earned and not given.
When respect is earned, that's when it actually means something.

Absolutely, it's the way the rank structure is set up. You don't need to know or respect the person, but you do need to know and respect the rank if it is entitled to a salute.