Whether it's with your time, money, skills, or belongings, generosity never goes unnoticed and most women find it a total turn on. If you're the first person to buy a round at the bar, or you love giving up hours of time teaching your nephew how to play baseball, or you're always quick to lend your car or other belongings to friends in need, you're definitely one of the good ones. Women love this quality because men like this make great dads.
Being cagey with your things indicates that you don't want to share your life with anyone. It could also signal that the people in your life don't mean as much to you as your stuff. You can see how women wouldn't necessarily love this in a man. Try to be a bit more giving in life and you'll reap the rewards.