Yes there were some build issues, but the same problems occurred in allmost all the Victorian built slums - buildings which where well built.
Not true! The maisonette I lived in was one of the better ones, yet it had noticeable issues, such as poorly fitting windows which the new town development authority couldn't be bothered to fix, so I packed the gaps with newspaper and applied mastic (expanding foam was still in the future back then). That block, and many others, was subsequently condemned for
structural defects such as rotted ties and blown concrete well before its' time. Over the years I've talked with people who lived in this sort of housing in Cwmbran, Harlow, Skelmersdale, Stevenage, etc who all complained about cold, damp houses, poorly built and poorly maintained. That was very common in 1960/70s new town and social housing, so much so that many, many buildings were demolished early.
As to Victorian slums, I feel that you may be too young to remember the massive slum clearance programs undertaken in the 1960s and early 70s - programs which saw wholesale compulsory purchase of large swathes of back to back terraces, under dwellings, of houses with rotten bricks or still with beaten earth flooring, with outside tip toilets or communal privies, and so on. many of these properties were cheaply and shoddily built (Jerry-built), but most of the worst Victorian housing had disappeared by the 1980s, which is possibly before your time. So no, not well built at all
I've been involved with lots of post war system builds on the estates, and my view is that when you see different families in similar housing, but not experiencing the same or any issues, then it must be the people who are the main factors, not the buildings.
I'm pretty sure that all of us who are in the trades have done some council house bashing at one time or another. I recall the ones which were spotless, and some which smelt dreadful and where you'd think about wiping your boots on the mat
as you left. But I still feel that planners and architects are partly responsible for the malaise which often besets public housing - for example the homes heated (as mine was) with electric heating that even someone on a decent wage struggled to pay for because the heating was so inefficient, and so expensive to run in a very poorly insulated building. No wonder, then, that poorer, less well educated tenants found themselves making a choice between heating on electric and not eating, or using a paraffin or gas heater (with all the condensation and black mould that brings) and still being able to feed and clothe themselves. Yes, electric warm air heating in the 1970s was that expensive, and when we were in the middle of miners strikes or a three day week (due to a war in the Middle East) and there was no electric for heating, what then? As I said, I was fortunate - many weren't at a time of 20 to 30% local unemployment (if you want a really bad example look at the statistics for Skelmersdale after Courtaulds then Thorn pulled out in the early to mid 1970s, around 45%). It isn't always down to what blood-sucking scumbag landlords call "scumbag tenants"