Very interesting subject. Some thoughts that come to mind that I have witnessed are the following : (These are not necessarily disgusting but certainly at least one of the players was annoyed)
case 1; my game ran long and into the lunch hour so I didn't get to eat before the next round started. My opponent came in with a big double double Burger, Large Fries and a Giant Drink. While my stomach growled, I had trouble focusing on anything else.
case 2: I once beat a player rated over 300 points higher than me in the Southwest Open in Dallas Texas. I noticed he was very finicky about the placement of the pieces and the board and would say I adjust when his move started and then put any piece I had sloppily placed back into the center of the square. I proceeded to say I adjust at the beginning of my move and place all of just my pieces randomly way off center near the corners of the squared and turning the Knights to random facings also. He would readjust and I would re readjust and so on. If I took a long time on my move he could not focus on where the piece were and in just a few moves he started to get into a bad position, which I was able to win. Know your oponents weaknesses.
case 3; I did not see this game but had it told to me by the very strong player it happened to. He was playing a critical round against a French Defense played by a young fellow known to be fanatical about the French Defense. After both sides followed the main line down a dozen moves, the young man broke from the move order in the book and put a knight on an unprotected square. Now my friend knew the young man was up on all the latest theory and he thought there was a chance for some tricky counter play if he took the apparently free piece. When he looked up at the young man he was smiling and had his arms crossed across his chest, looking like he had already won. Since the game was critical to the tournament and since he feared a trap. He didn't take it and the game went on for another 60 or so hard fought moves. After the game the young fellow admitted it was all bluff. He had made a mistake with the move order and thought the bluff might save his piece. It did save the piece and gave him a chance in an otherwise quick loss.
case 4: The tournament room on the first round of a 5 round swiss tournamen was very quiet as everyone started their clocks. The person paired with the second highest rated player had heard his opponent talking before the tourney about wanting to concentrate and make play his best chess for each position and not be sidetracked by his opponent. He took him at his word and played and moved quietly and slowly. When the clock was pushed, it was pushed slowly not making any click or slap. By the tenth move 45 minutes had passed and the lowly challenger took to slipping out of his chair and going out of sight across the room on his opponents move so as not to give him any stimulus whatsoever. By move 15, with no pieces yet taken on the board, the High rated player had a beautiful position, and was surprised to find his opponent telling him his flag had fallen and he had lost on time.
I'm an old ex-tournament chessplayer, and I thought I'd share how I've been disrupted over the years.
A guy in a club match, a really fat, sweaty disgusting guy that lived with his mom, had his fantastic looking 'girlfriend' come behind him, bend over and give him a neck massage, revealing her nice cleavage. Repeatedly! I was later told he'd hired her.
A guy in a tournament kept picking his nose and eating it, then adjusting my pieces.
Playing a blind player disturbed me, especially when I had to resign!
I'll add more as they come to me, feel free to add your own. This is the Trump era!