A taste in music is a trait, or at least I think so. I use it to find new music and share the new music I find with others who share similar tastes. Listening to music, discovering new music through listening I think is a hobby.
I don't mean to offend your interests or activities - I'm trying to make sense of the world we express through words. So far, I'm having difficulty justifying the status of a hobby of listening to music. It may be pleasant and even euphoric, but it seems too passive for such a definition. It's an activity and a way to gain pleasure and spend time, no doubt. I have no difficulty calling reading books a hobby because it requires active participation - otherwise, no reading occurs, or, perhaps, no understanding of what you've read, which is the point. But listening to music - at least, if you aren't engaging to it actively, with all of your mind's attention - is hardly an exercise in activity, especially when you do something while listening to music. I've never heard people calling taking hot showers a hobby, and most people won't call eating their hobby either. So, why is music-listening on the list?
I'm very critical of the music I listen to. Whether its lyrically, or instrumentally. I have a wide spread collection of music just for listening. I have friends and groups at my university that share music we find not necessarily to critique the music in any meaningful matter, but to share the experience of listening to the music. I would say that listening to good music is a hobby. Eating food can be a hobby. Food critics are very critical of the food they eat, but their jobs are simply to eat different foods, and explore taste. When I take a shower there is really only one way to take a shower, but there are an infinite number of ways to experience listening to music.
The only way I determine what good music (Music I like) is by listening to music all the time which is what I do. Listening to music is a very active part of music, and really isn't passive in any sense. If you are passively listening to music you really aren't listening to the music, you are just hearing it.