Would you tell someone if they are having a bad hair day?

No it is rude. They probably know already and can't do anything about it. Telling them would just hurt their feelings.

no i would not,prefer not to hurt that person

I like to keep my hair clean and wash it everyday. I also oil my hair and scalp and then shampoo it esp. with anti dandruff properties so that i have clean silken light hair. I am not too concerned about my hairstyle and keep it basic and simple.I care about my hair a lot and my hair style almost too much. I think the most important to give an impression would be hair. If the hair style and texture is right, it would give people of an energetic and clean feeling. It's also a self-respect.