When we say the sky is blue, we all agree (except those totally color blind), which is fine. However, while I know what I see is blue, being told the sky is blue from childhood, how do I know for certain that what others see is the same color? Perhaps what I see as blue they see in some other hue; we just refer to our individual perceptions of color through convention.
This might explain why some people find some color combinations in art work or other forms pleasing while others find the same garish.
The same could be said with other perceptions such as taste and sound which is why some music is pleasant to some but abhorrent to others, while some food tastes great to some while others vomit. This of course is genetic. It is known that some people can find PTC paper bitter while others with other genes do not. How much is nature and how much is nurtue.