Hair by itself never has a smell. So any smell good or bad entirely depends on what you are doing to your hair or scalp. There are many ways to make your hair smell good.
Never spray normal perfume onto your hair. It can make hair very dry and also cause damage to the hair. There are hair perfumes and you can try those.
Use a good shampoo with a nice smell that lasts long. If you use a separate conditioner, get one that has a good fragrance. Herbal essences, Tressme are shampoos that smell good.
Following the above steps can get you a good smelling hair.
Keep your scalp clean and wash it properly.
Food always influences the way you smell and your hair is no different. Avoid pungent food.
Smelly hair syndrome
Hair can give bad smell even if you shampoo and bathe regularly. This might be due to smelly hair syndrome. This happens as sebaceous and sweat glands in the hair follicle produce oils and sweat. The problem gets aggravated due to stress or hormone changes.
Coarse hair is able to absorb some of the oil. However fine hair cannot do as and the problem will be more acute here.
In this condition you should avoid using conditioners and also shampoo with care.
Fungal infection can cause bad odor in hair and result in SHS. These can spread due to sharing of combs and some of the fungi come from pets and animals directly.
For SHS consult a trichologist who will identify the cause and act accordingly. For fungal infections there are pills that cure it.
One of the considerations while buying a hair perfume should be that hair absorbs more perfume than skin. And hence it will disappear faster than normal perfumes if used regularly.
Aquolina Pink Sugar Hair Perfume
Viktor & Rolf Flowerbomb Hair Mist
Dessert Beauty Deliciously Kissable Hair and Body Mist
Thierry Mugler Angel Perfuming Hair Mist