Vacuum cleaners are funny. The act of vacuuming is at least as important as the dust removal itself. A freshly vacuumed rug looks different... but in the short run, there's really not a lot of visible difference between a rug vacuumed with a really expensive machine and one that was poorly vacuumed.
As a result, the worldview of the buyer matters a great deal. If you see yourself manhandling some big loud device, then only a big loud device is going to make you feel as though you did what you were supposed to do.
We've done the Dyson story to death, so I won't go into that here. But I got this ad from Francesco Rovati in Italy, and it made me think about the alternatives. Francesco confesses that while this was the most popular vacuum in Italy, it was no better and no cheaper than the alternatives. Clearly, it was the story the ads tell that made the thing sell.
The reason that vacuum cleaner makers tell us lies like this is that we demand it. If they just told us the truth (weight and horsepower) they'd be doing nothing at all to make us feel good while we vacuum. And feeling good is why people spend their hard-earned money on things that they don't actually need.
(PS the ad with Tarzan losing his loincloth was too racy for this family-friendly blog).