As for smoking, if companies were allowed to actually misstate it is good for you, there would be myriad other organizations working to prove it isn't. A reasonable person might well do his own/independent fact finding.
Someone can say eating an octopus is yucky [it is actually used with salad in many places] but for a large amount of money you can convince/bribe them to try it. But if Warren Buffet says no, good luck bribing him. You can try another [practical, not theoretical] incentive, but I'm sure he could buy that too. One can say rich people must live certain lifestyles, but Steve Jobs lived an almost monastic life [save the Mercedes and a couple of other things maybe].
That inherent need has to be present for an advertiser to target/exploit it. And the person has to actually buy the premise of the proposition. Many have the guts to go against the crowd and some even take it as a badge of honor.
Valentine's day is a manufactured custom too. Many are religious about it, many others abhor it - despite the concerted, and mostly successful, efforts to create a romantic custom out of the day. Diamonds, I agree - in many cultures, especially the US. But in many other cultures, such as the Nordic, it is less common [1 - a forum thread]. That doesn't mean de Beers doesn't try its level best to manufacture the same kind of social custom in Sweden. That need for extravagantly showing off a romantic pre-commitment just doesn't exist in that market.
Now let's reasonably assume your SO is well aware of the hiring-pretty-girls-policy, and does not prefer you buying from that store given that there are better economic alternatives, and add in a touch of reasonable jealousy. Do you still frequent that store, given that you are happy with your SO?
Could I sell you an extravagant snake-oil panacea if I were a hot bird?
[1] http://www.thelocal.se/discuss/index.php?showtopic=32620