The snog-with-dialog rises almost to a Hitchcock convention. It was pioneered in Notorious (1946), when there was a limit on the time a kiss could last. Apparently, there was no such restriction on how long two people could press up against each other, so AH used a seemingly eternal embrace between Cary Grant and Ingrid Bergman to create the impression of one long kiss. At one point, Grant moves over to use the phone, and does so without breaking the clinch. Before the phone call, between kisses, the two make their dinner plans. They’re having chicken.
There is another example of this in North By Northwest (1959) when Cary Grant and Eva Marie Saint spend the night on the train. But the best use of the device is in RW, when Jeff attempts vainly to get Lisa interested in the Thorwald mystery while Lisa tries vainly to interest Jeff in her. The working-at-cross-purposes dialog, and the resulting frustration, produces a very comic scene. More than that, of course, the scene very deftly illustrates the conflict between the characters: he’s all business; she’s all romance. Thus Hitchcock’s genius. The pet-and-palaver routine–heh, I’ve got a million of ’em–originally conceived as a method of by-passing the censors, has become the means of articulating theme.