@Isaiah4031 There are other things I personally consider bad manners which I fully understand is not, such as offering takebacks or offering extra time, not to mention actually requesting it. I never do this, although I tend to accept if someone else does. If I happen to make a losing mouseslip I simply resign and move on to the next game.
But this is how I'm conditioned to react. I'm the "I'm here to play chess, not to socialize" kind of guy at the chess club. I'm generally easygoing and not very competitive but Chess is Chess. Just wanted to point out that what constitutes good manners/sportsmanship for some can be the opposite for others.
As this is a thread about sharing good experiences and not about debating I'll share one thing which I'll never forget:
I was sligthly under pressure as black in a 5-minute game. I had found a very counter intuitive and "sneaky" queen move. All of a sudden I had the initiative. My opponent thought and thought and then said "gm". I wasn't familiar with the abbreviation but soon realized it meant "good move". This isn't very spectacular in itself; but to me in that moment, and because of the very nature of the move, it just made my day.
So now I actually try to say something when my opponent makes a move which I find pleasing for some reason, especially if he's significantly lower rated. I find this to be equivalent of the very slight nod I would make IRL to aknowledge the strength of my opponents move.
Others are of course more expressive but I enjoy the under stated.