I know that the artist responded already, but I also think that it's "dirty" because it's supposed to look like an old photo, like an old memory, and yet, there are parts that are very vivid. Just like an old childhood memory or something. At least, that was my take on it.
in reality I don't like DA because people write positive comments. But noone is able to say what he doesn't like about works, he's commenting. I would better take into consideration some critics rather then positive wow and ohh!