I didn’t react to the hair color that much. Probably because it’s what to expect from a ‘Korean’. Where I’m from men don’t tend to do makeup and women don’t do that much beyond what would be obviously noticable. In essence, you don’t ‘brag’, while in Korea it seem the opposite, if you have money, you buy expensive cloth, cars, hairstyles etc. So it’s became normal whatsing kdrama. However, what I do tend to notice is how ‘slime-y’ the hair is, that is it reflecta light from all the gel/vax used, and was happy it wasn’t. 
The decision he made was more the thing at the end that made it go on my nerves, so cliche and predictable.