Have flown in a few dirty cockpits in my time and it isn't pleasant. Companies tend to shy away from paying 'proper' aircraft cleaners (I mean flight deck, not toilets/ cabin), presumably on the grounds of cost. Engineers often get burdened with it and (not for any particular reason) it often just doesn't get done.
As for pilots cleaning the cockpit, well, certainly tidying your rubbish away and following the example of meatball is to be commended. It is the more permanent grime that is the real problem and pilots don't have the cleaning materials and clothing to do this job, let alone the time to be crawling around on the floor pre/post flight.
What is really annoying though is the guy who uses the sani-wipe to clean the PFD screens after he has cleaned the headset and control column. It leaves smears all over them and is totally unsuitable for the job, leaving them less clear than the film of dust!
PP