Once I saw SQ employees in the jetway at TBIT for the LAX-NRT-SIN flight. They were grabbing large carry on bags, such as those that would barely be legal on USA carriers and aggressively gate checking (for free) those that were too big or too heavy, including the wheeled bag of one unhappy business class passenger. Another guy argued that he had medical equipment and was allowed to keep the bag, IIRC also in business class.