Have a white cover since October and, boy, it attracts dirt quicker than my vacuum cleaner… I tried car wax, but that did not help. Regular cleaning helps, but makes me crazy - it is a phone and not my hobby. So I decided to go for the “used look” and now have a unique greyish back cover 
I still like (real) white most, but would certainly not decide for this again.
And by the way: There are a lot of white phones in the market that stay white. Part of sustainability is durability.