Cool means different things to different people.
It's nearly impossible to use "cool" as a standard for creating or judging advertising as everyone will have a different point of view.
I might think turquoise bolo ties are cool (I don't!), you might think Ed Hardy ties are cool (they're not!), someone might think a.p.c. ties are cool (they are!) and someone else might think not wearing a tie is cool (depends).
I write for Apple and I think Apple products are cool. Apple ads appeal to people like me and convert people like me from PC users into Apple users. But most of the planet does not think Apple is cool enough to buy it or use it. At least not yet. So "cool" may also limit your target audience.
If a product is useful to consumers, they will decide if its cool or not. I don't think the manufacturer or ad agency can decide this. So when a client asks me to write "cool ads," I always give them this little speech. It usually works—except when the client is not cool.
