Azek cut edges gather dirt

I recently trimmed out a porch using Azek (and some Versatex) vinyl 1x trim boards. While the faces look great and clean up easy, any where I have a cut or routed edge, it tends to get dirty very fast and looks bad.

I've tried cleaning first with TSP, then at the recommendation of the Versatex rep. used acetone. The TSP cleaned it up but it looked dirty again after a month or so. The rep told me that acetone will help by closing up the pores, but so far that appears to be only a marginal improvement at best.

I'm sure part of the problem is the contrast between the bright white face contrasted with the dirty edges. But the entire purpose of using vinyl was to reduce maintenance, not add cleaning every couple of month or so.

Has anybody else had this problem? If so, has anybody found a fix?
Thanks,
Tom