It's so simple: " Dress pants and shirt are required for men and a dress or pantsuit is required for women. Please no jeans, shorts, capri pants, flip-flops or tennis shoes." Clear, reasonable, generally enforced, comfortable.
You have heard here of folks being admitted with polo shirts or capris, with people calling it a "party" dress code, and with nice jeans being admitted. Yep, I've heard the same. A polo shirt is clearly not a dress shirt, and Palo code is that you can't wear one. Yep, people get away with it and have had a great time there.
But...if you follow their dress code you will absolutely have zero problem. Guaranteed. If you push it based on others' reported experiences, you are risking the Palo management asking you politely to return to your cabin and change to follow the dress code. Why even risk that? Palo is wonderful, and their dress code is pretty easy.
As for the MDRs, sure does feel like anything goes, based on our recent few cruises. And most everyone seems comfortable and is having a good time. Gone are the days of everyone dressing up for dinner, time moves on.