[Skyboi]

To be honest with you.... I think it's the nature of this type of grille.
First it looks real shiney and really fools a lot of people into thinking it's real solid but in reality it is just plastic....It flexes over time and the small cracks add up until there is now no way to really clean them absolute.

It's like the law of diminishing returns...The more you clean it the less it looks clean. It's wear and tear.
(I know that someone is going to chime in about the law of diminishing returns so...In terms of what we can all understand, If you were heading out at night determined to drink beer....The first one would taste great...But the law states that each additional beer would not actually be as satisfying as the first because of other factors....your tastebuds would be used to the flavor and start to become desensitized and your judgement would start to be imparred....you get it)

If it really bothers you I would recommend either purchasing a grille to replace it (pretty cheap) or going with a billet type and giving your truck a new flavor, this may help you re-appreciate it also.

Just my 2 cents