i've encountered singaporean ungraciousness too in Marche (Vivocity). i was sitting next to a table of a group of 10 twenty-somethings. from their look, i reckon they are u-graduates and some could be holding a top jobs (from the things they talk about).
well, the story is, after they've eaten and their tables cleared of crockeries, they remained at the table talking-****, sing-song and play mahjong. all these while, not ordering anything to eat. this goes on for a good half-an hour or so.
the duty manager have been seen asking them (a number of times) if they would still want to eat. if not, would prefer if they give up their table bcoz the restaurant is damn crowded and there's a long queue outside. however, this bunch of people are still at it without eating. they sat there for a little while more and then finally made their way out.
i was thinking, these are the future of singapore and it's a shame that such a behaviour is still seen. the effort by the government to promote a more gracious society seems to be fruitless.