A great example of this is Ben Howard
This slouchy look is a particular fashion look shown in the majority of Acoustic artists. This portrays the idea that its not all about fashion, or selling the style of the artist. It shows us that its about the audience, and therefore fashion and style is not something that is important withing this field of genre.
Here is another artist that shows this style well. The Surfer image on his t-shirt shows the idea i said earlier about the lifestyle of the artist. Xavier Rudd, is an australian surfer, of which takes pride in his musical creations, and not his image for marketing his music.
On the other hand, this band, Mumford and Sons, shows the fashion/costume idea which i would like to portray in my music video. The suit and jeans look, posh but casual works really well with their band and the quirky personality of their music. I think my track has its own style, and therefore a quirky fashion sense such as this would work well for my music video.