parts of our station, particularly those around 73rd, are extremely nasty. and i do think it has a lot to do with the privatization deals the MTA has cut to save money. that's why escalators go out of service for months, even years at a time (see Union Square). they issue fines against the property owners, who pay them and continue to ignore repair orders, since it's much cheaper to pay the fines.
it's really all about cash. if there's money to be spent, it's going to go to track work and train repair before it's going to go into station cleaning. and since this is a zero sum game, i'd prioritize train service over stairwell cleaning as well. it'd be nice to be able to say 'well, we deserve both,' but realistically there is a finite amount of cash there, and it's not terribly well managed -- much like road repair, police efforts, public housing and so on.
and for what it's worth, i see power washers with bleach working on the mezzanine and inner stairwells pretty often -- right around one AM, usually.
Take a tour around every borough, and you will see that our station is on the same level of dirt & neglect as most stations. For me, this is a much bigger MTA topic, why can't we have a cleaner subways as a whole, regardless of the specific station.