These people are having fun. They are having fun with their clothing, and it is apparent. Seeing this confidence makes their clothes look good. It does not matter the brand, the designer, the country of its origin– if the article of clothing is used as a deliberate expression of self, no matter its make, it becomes like paint for the artist; used to unlock a bit of the beauty inside of the individual.
This externalized self is a glimpse of beauty– beauty is being simply you, and having the willingness to express who you are.
Being comfortable in your clothing exudes a sort of confidence, therefore beauty is not dependent upon your clothes, but upon your state of mind when you are in your clothes. A sense of self and recognizable comfort.