I received this pair of socks (the blue one) from an online clothing recommendation service. But I want to return it because I think the color is too strong for me to handle or pair with other clothes. What is the most precise word that I can use to describe that this sock is too strong in its color and too challenging to pair with other clothes? I am not satisfied by just saying that the color is too strong/bright/colorful.
Garish or gaudy mean bright or showy in a tasteless way. If you're not actually trying to insult the socks, you could call them flashy or loud.
You could also say they clash with everything.
It depends on the exact lack of appeal you want to convey. If you wanted to suggest that they made you feel "sick" or "turned your stomach" you might say they had a "bilious"color combination (could be especially useful if they had the color yellow in them).