Should retired officers, who are not in uniform, return a salute?

A salute is a greeting between military personnel, including those of who are retired. It's not an obligation, at least to me, but a privilege. I take pride in saluting. I understand how you may feel. I would say that, retired REFRAD, if you feel like acknowledging the salute with a return, do it. If you don't, at least smile and, if the windows down, say "Good day."

Not required, but I would say respect, honor, might support it

Why would you not? You were shown a courtesy. Return it, geeze!

I too am retired. I return all salutes. It costs me nothing and to fail to do so is a rejection of the military courtesy offered by the one offering the salute.

If you are Retired, whether you are a GO or a Private, you retain your retired rank. You should return a soldier's salute.

One of the best things to come along is when anyone of prior service, regardless of dress was allowed to salute our Flag rather than put my hand over my heart like a schoolboy, If I can salute our Flag, I will surely salute any officer who served that Flag. Get a grip LTC , those salutes are EARNED NOT `GIVEN.'

HECK YEA!!!! I understand if you read AR 600-??? it will tell you this that and the other thing. However, if (in my opinion) people who know you are still Saluting you and still doing what they are suppose to do when they see and still treat you as if you were still in then rendering a Salute back is the approaiate thing in my opinion

yes. If they show you respect of your rank even retired. Then you should show respect, to there acknowledgement of your rank.

If they are showing me respect / courtesy and render a salute…. I will not disrespect them but not returning it.
I do not insist or solicit a salute. If they call me “Sir”, I tell them “no, it’s joe. But thank you.”

I am confused by your statement. Did you resign your commission? A commission is for life unless it is removed or taken via court martial. From Military.com "When an officer retires, their commission normally remains in force and effect forever. In return for the privilege of being legally entitled to being addressed by their military rank and getting all their retirement benefits, they basically remain an "officer of the United States" until death."