Why is everything so dirty?

Now I've been to the Philippines many times before, so the scenes that were supposed to be there felt real enough (though obviously everything there doesn't look like that). However I didn't expect 1960s Hong Kong to be so claustrophobic, with buildings upon buildings, in such an unkempt kind of way. I mean *everything* looked like it needed a new paint job; even the Yuddy and his mother's place wasn't all that great. I would've expected their place to be at least decent looking, as it was implied that the amount of money in the monthly stipend was enough for a comfortable life.

Was it a directorial choice (and if so, why), or was it an accurate depiction? I've been to Hong Kong plenty of times as well but only in the mid-90s onward, and it's obviously a huge change from back then.