People, like myself, who has dyed or continues dyeing their hair tend to have the same thing said to them: "You can't have your hair dyed a color that isn't natural." What they usually mean is that hair can't be dyed a color that isn't natural to human hair color, however the color itself is natural in nature.
My favorite color is purple and for fun, I dyed my hair a dark purple color, "Purple Desire" from Splat. I tend to get a lot of looks by people, however I haven't met many people that didn't like it. Only people over a certain age have told me that dyeing my hair purple was "stupid and irresponsible."
"It makes you look like a hoodlum," is something else I was told. I disagree, I don't think my hair dictates anything about me other than the fact that I don't care what other people think of me and I like my hair this way. The younger generations are more lenient when it comes to the way people look and I think it's because we are caring less about it. However, the older generation has a notion of "public appearance" that gives them the thought that people can't have something that makes them stand out. It's about the business look for those folks and if you didn't look "professional" in their head then you can't be one.
But the way someone looks doesn't tell you how smart that person is, how professional they are or how serious they can be. It does help to appear to others in a certain way as that is the first way people will judge someone, but appearance isn't the person. If someone like Albert Einstein had dyed his hair something odd, like blue, people may not have thought of him as an intelligent scientist, but he would have still had his mind and would have still developed the same theories his hair color changes nothing about that. I think if people like him, who were very well known and role-models, did dye their hair we wouldn't have such a lower opinion about it today. When someone talks about someone else; they don't say, "and they had brown hair, they must know what they are talking about", but if someone had "unnatural" dyed hair you surely would hear that their hair is pink. It's interesting as it's unique, but has no other info to really give other than its uniqueness.
Saying colors like blue, pink, purple, green, or any other odd hair color is unnatural is wrong and just the person's excuse to not liking the color. By genetics human hair can't be certain colors, this is true however, the colors are still natural colors, we just happen to have our hair that color. Blue is in flowers like tulips, it's the color of the sky and water, and it's in the color of scales on fish or feathers on birds. Purple is in flowers as well like lavender, lilies, or a lotus. Purple is in fruits like grapes, plums, eggplants. Animals have purple in their appearance as well. These colors are natural and are found everywhere else in the world, but apparently if it is in human hair then it's suddenly bad. If someone doesn't like dyed hair then they shouldn't use the "unnatural" excuse, they should just say they don't like dyed hair.
Someone's creativity can come out as them wanting dyed hair. It is unique and, much like clothing, it can be considered a fashion and just an appearance to most. Certain colors are considered to alter people's moods as they look at it. Blue is a calming color that helps people communicate better, so it's used for business a lot as a result. Purple is considered the color of imagination and individuality as well as royalty and mystery. I love the color purple for its mysterious sense and imagination as well as it seems to be calming to me. Purple is used in life as a royal color, so it's used for luxury items commonly, although it's perceived as spiritual as well so it's used in things that has mysticism to it. Colors help people communicate things non-verbally and help set/alter the mood of the people around them. Someone with this knowledge may dye their hair a color that suits what is needed in an upcoming conversation.
Many clothing fashions don't get hassled and are tolerated, but fashion dealing with someone's hair tends to get the odd comment every now and then. If we don't make a fuss about someone's apparel why would we just because their hair is colored; our clothes are colored so, why is the hair so bad. Hair is protein filaments that consist of Keratin and continue to grow much like fingernails. Hair isn't permanent, you can cut it and it will grow back, except for the people that lost their hair from stress or age. If someone didn't like their hair, they can cut it or let it grow out and change it. Dyeing hair isn't permanent either, sooner or later the hair will grow long and it will need to be cut resulting in the dyed hair being removed. In many cases the dye just washes out over time and would need to be reapplied if wanted to be kept; It's temporary so why do people make a fuss about it if they don't like it?
Dyed hair means nothing, it tells nothing about the person and it changes nothing about anyone or the environment around them. It can be used to change moods, but even that is only a suggestive thing as it doesn't always change the mood as directed. Hair is temporary so it doesn't matter if someone doesn't like it, it'll wash out or be cut at some point and it could also just be dyed again. The actual person underneath the dyed hair may be very different to the assumptions that some else made about them. Color is just a color in the end and hair is just hair, people shouldn't judge others based on either of those topics. People should make their own opinions about a person with dyed hair by talking to them, ask them about the color of their hair, maybe the reason it's dyed would surprise people. Sometimes it's just dyed because they like the color and want to dye their hair and there is no other meaning to it.