To be honest, I don't think impulse buying is a bad behavior.
Of course, falling into shopping mania and purchasing impulsively everyday is crazy, and It is even worse when you need others to afford for your bills.
Sometimes I purchase on impulse, when I suddenly capture a beautiful handmade earrings on the street; when I see a interesting book in a bookstore; when my mom try a dress on that fits her perfectly...I can list down countless occasions I spend money on impulse, but I think it all worth, it is the way money brings us happiness, and also my motivation to make more money.
Besides, I think character also has an influence on this, people who are impatient and decisive are more likely to buy impulsively.