If I had to boil Freud down to a single proposition, it would be that some methods of self-control run so deep that a person never becomes aware of all the impulses s/he is regulating, BUT (to add a 2nd proposition) we CAN observe the impulses that are unobservable to individuals through society's symbolic matrix of prohibitions et al.
The big innovation of Edward Bernays is to provide slogans that are actually heuristics that make aspects of social reality (eg women smoking) legible to modernist instruments of social sense-making (the news).
It doesn't really matter whether public relations are influential. The advertiser creates the capacity for observers of society to perceive new categories of behavior. The advertiser sells the capacity for self-regard, via modernist media, to their clients.
By selling clients on the view that consumers were exercising self-expression, advertisers are actually selling them on the idea that metrics like sales figures are profound expressions of meaning-making from below rather than statistical noise or sectoral indicators. Advertising is meaning-making from above, for clients, but with a modicum of displacement.
Most of Bernays' stunts rely on triggering the observable mechanisms of suppression. The Freudian logic, again, suggests that society can explicitly censor that which is deeply felt but innately censored by an individual. To trigger someone, it follows, is to grab them by a handle on the inside that the individual can't even grasp. But again the trick here is in telling a story that the real meaning is that individuals are in a crisis about confronting some taboo.
I hate to be all "sometimes a cigar is just a cigar" about this, but I'd argue instead that scandal in media is just a kind of pseudo-event that helps smoothe over a problem in the distribution of those media: we don't get 22 minutes of news each evening, or 1 paper's worth, so pseudo-events help bulk up thin editions.
The advertiser needs the client to believe that the spectacle of censorship is deeply felt by the audience. The news office needs the advertiser. And so on.
There's a lot of phony arguments that are made in support of the advertiser's lore. Sure, you can point to the libidinal base for lots of personal habits. But it remains to be demonstrated that those habits are responsive to stimulus, that they're responsive to the specific media being applied, or that they're responsive in predictable ways.
It's no wonder that Herbert Hoover, the engineer, was enamored by this approach. It's all based on an impersonal, hydraulic treatment of humanity: put this in the press and sell 32.7% more cigarettes, eg. There's fundamentally no interest in any individual person as an autonomous source of their own meaning. To be interested in that, for Hoover, would be like respecting one inch of pipe among others.
You really have to start wondering about the metaphysics in some of the Freudian stuff on mass psychology. It describes groups lending their libidinal force to dictators. This implies some kind of psi that flies in the face of all other natural scientist. This is invented as backfill for the hydraulic metaphor: people are pipes, so there must be some effluvium running through the pipes.
Whether you call it psi or libidinal investment or influence or attention, it's all backfill lore for a story that advertisers are selling to clients. It is essential, above everything else, that the clients believe that advertising has causal force. The advertiser must be understood by the client as a rentier selling access to a hydraulic system of coercion.
When the advertiser gives the client some metrics and some spectacle, the client must believe that the spectacle caused the metrics.
When someone like Walter Lippmann says that the advertiser's lore (unthinking masses triggered by the manipulation of deeply felt taboos) should justify a new technocratic elite to control the mechanisms of media, he's really just adding a layer to the lore and helping clients believe that they're accessing the control room of society.
The dull reality, of course, is that advertising clients are simply accessing the the production inefficiencies of media technologies.