Tend to agree with those who say that the state of the interior gives an indication of the general maint culture of the organisation as a whole... a grotty cabin naturally raises questions as to what other corners are being cut.
Then again, I was once in a Qantas DC-4 going up to NLK when we passed through a rain squall and the lady next to me had to open her umbrella... the old girl (the a/c, not the pax) had sprung a leak...