Most Commercials Aren't Aimed At Engineering Types
Here in the Boise area, there are these radio commercials for a central vacuum company that feature a kind of clueless dad (nowadays, what other type of dad is there in popular culture?) who is always wondering what he could do with his powerful central vac if he were to "reverse the polarity". (These things include launching things into the air, blowing out drain clogs, etc.)
Most people, when they hear that, are probably thinking something like "well, I guess the vacuum must be pretty powerful; maybe it'd be useful in my house to pick up dirt." Engineering types, though, don't react that way. We hear a commercial like the most recent one this company has out (where the dumb dad is going to "reverse the polarity" and attach it to his wife's SUV, so the air blowing out will push the car along and save gas) and we start thinking, "Wait, a vacuum pump is like any other centrifugal pump, it's built to work most efficiently in one direction. Why not just put it on the way it's designed and pull the van along by sucking air in?" We also think, "You're going to have a lot of losses in the alternator, converting gas to rotational motion of the engine to electricity. Combined with the inefficiency of the reversed vacuum motor, they're going to end up using more gas."
Bottom line, if companies want to advertise to engineering types, they need to get smarter ads. Or really attractive spokespeople -- those work too.