Yesterday I had an opponent do this to me toward the end of a tournament game. They passed twice while I closed a couple of open boundaries. I knew that I was losing badly, but the game was almost over and I had been playing quickly (more or less live in a correspondence game) with reasonable although not outcome-altering moves for the second half. I stopped looking for open boundaries and responded to one of their passes with a pass, and the game got scored with a large chunk of both of our territories left uncounted because the boundary hadn’t been closed.
It wasn’t an enjoyable experience for me, and as for my opponent, it left me wondering why had they entered a tournament that clearly promised such large mismatches? (It was about a 6k difference in rank, played with no handicap.)
It also left me wondering why I had patiently suffered through that one ladder game that took forever against an opponent who seemed to have no idea how to play the game, but I hadn’t wanted to be impolite. That experience just wound up weakening my initial enthusiasm for ladders, and I wound up leaving most of the ladders I had been on.