I think you'll probably find that their fleet is better than most, particularly the suburban operations. Have you travelled much on Northern's, for example?!

Or closer to home, Southeastern?! Their Sprinter fleet is without exception the best in the country, not only in terms of reliability but also cosmetic upkeep. The 458's have apparently been totally turned around in terms of reliability thanks to the efforts of SWT after they decided to retain them.
I have to say I think the refurb of the 455 fleet was excellent, though like
junglejames I'm not a fan of the Desiro-spec hard seats. The trouble with the London 'metro' network is that whatever rolling stock you use, no matter how nice it might be, it will quickly get trashed by the lesser elements of the travelling public. There is only so much money that a TOC can reasonably allocate to removing graffiti and repairing cosmetic damage like etched windows etc, particularly when it will without any doubt eventually reappear again. Sadly this can give the impression that nobody cares, but in reality I don't think that's the case at SWT. As for cleaning though, only they can answer any questions about problems with that, perhaps you could bring it to the attention of one of their managers through the various channels available?