According to a study by MTV Networks, among 18 to 24 year-old respondents in Germany, India, Japan, the UK and the US, the most popular features of a brand were good quality, trustworthiness and workability; a cool image only comes in the 4th position.
In each country, a majority of respondents reported that the Internet makes choosing brands easier. The data highlights the “need to engage in comprehensive 360-degree campaigns,” said Jules Robinson of Viacom Brand Solutions International. Just in case you had not realized yet…

Interesting.
But I wonder if their behaviour is consistent with the answers they gave…
A cool image can often provide the brand with a ‘halo effect’ which in turn will improve their perceptions of the features above cool in the list.
I’d like the see this question asked about specific brand categories, I think ‘cool’ might be a lot more important for clothing brands in comparison to cleaning brands.
@Matt: According to this article from the New York Times, looks like clothing brands are not spared:
http://www.thetrendwatch.com/2009/04/23/teenagers-really-care-less-and-less-about-your-brand/
A cool image is obvious. We won’t even look at quality and trustworthiness if the image is not at all cool. There are plenty of reasonably cool good products out there – so we can be picky.