I always find it quite curious when people ask me why I have so many books on my bookshelf. Some people think I am simply adding to a collection that never gets touched, others may think that I am feeding some form of materialism or compulsion. Regardless what people think, it is obvious that a bookshelf full of opened and unopened journeys says a lot about a person that we should all consider the next time we run across one splitting at the seams.
Your collection shows a desire to learn. Look closely at the person's selection, one-by-one, and see what the variety is. A bookshelf that has a variety of fiction, nonfiction, poetry, self-help, business, science, etc. shows that they are very open to new ideas and perspectives and is willing to learn. They are willing to put the time and effort in to exercise patience and expand their knowledge, and therefore can hold conversations with a variety of people.
It shows what you value. Each collection can describe what a person values most in their life. If the person has a healthy collection of business books, one could assume that the person cares about their development as a professional. When you find a collection that has an abundance of self-help literature, it probably means that they value making themselves better from a more general and personal perspective. Regardless, each book is adding something to the person's life that they can carry with them forever, be it a lesson about life, a new idea to think about and add to their values, facts about the world around you, or helps you discover something about yourself that you never knew existed.
You are not afraid of commitment. When a person has a huge collection of short and long novels waiting to be read, it shows that the person is up to a challenge. They have recognized once before the reward for hard work and staying dedicated to a prolonged task/activity, so they are ready and willing to put forth the effort to enjoy the fruits of their labor after they have completed the novel.
You are not afraid to disconnect and dream for a little while. So many people get caught up in the ebb and flow of every day life and its periodic monotony that they forget what it felt like to dream; to disconnect for a little while and simply unwind. A handsome collection of books shows that the person is more than willing to step away from the distractions and stresses of life and walk in the shoes of a fictitious character. When working a full time job, having this ability to unwind and disconnect allows the body to recharge and keep your mood and health intact for a longer, happier every day life!
Having a large, somewhat untouched collection of books on a bookshelf is not a bad habit, nor is it a social faux pas. A collection of unread adventures may say something else about the person's desire to be a better person every day, and may give them some new ideas to spread to other people, which can ultimately change the world in so many different ways. So don't take it personal, keep buying those books!