Where did anyone learn that after boarding a flight, it’s socially acceptable to take off your shoes? The other day in row 3, which is bulk-head, my seat mate took off his shoes and propped his feet up on the wall in front of us. He didn’t take off his socks (which I have witnessed as well), or have holes in them, but nonetheless it is rude. And when passengers in view itch between their toes, it 
especially engenders the urge to hurl.
Anyway, socks off doesn’t have anything to do with being in first class, it is just as rude in any other part of the plane. It was a major distraction to me as well as the Flight Attendant. Mr. Inconsiderate had to lower his feet every time our Flight Attendant wanted to serve, which is quite a few times in the first portion of the flight and through the time when the meal trays are retrieved.
I also remain bewildered that no matter what time of year, there are always people boarding a flight wearing a tee shirt, cargo shorts and flip flops, regardless of where they are going. Even though it was about 70° in Fort Worth on this day – where this plane was going the wind chill was 19°. If the flight was to Nassau, I might get it.
Unless you are walking around the pool, on the beach, in the locker-room, or generally in the privacy of your own home, flip flops are not appropriate. You may be comfy, but at the expense of being generally inconsiderate. We don’t want to see your feet, and least of all, rub or pick your feet on the plane. We can’t exactly walk away from such ill mannered behavior. And, that goes for women too; although there have been some exceptions, mostly depending upon weight class and pedicure, i.e. my wife has beautiful feet, but when in public, are donned with an appropriate dress sandal.
Next, why do parents allow their kids to wear sleep wear on an airplane? There must have been at least two families of 2+ kids each, all wearing bed clothes and carrying their pillow from home. The thought of cooties came to mind. This flight was at 11:00am. Don’t these kids sleep at night?
It is not about rights! We all aren’t or can’t be thankfully, Bret Pett and Antijolie on our private jet, where how we dress doesn’t affect anyone. I suppose you have the right to wear just about anything on a plane, but why. It seems that exercising that right sometimes crosses the line of decorum. I am not against wearing comfortable clothing and do so myself, but when you know you are going to be in confined close quarters with others, it seems appropriate to dress accordingly.
There was a time; and to a degree, out of the respect for others, when people dressed up to travel, even if just a little.