Garishness is a pet hate of mine. As usual I'm strapped for time, so I'll hurl some contentious(?) issues in the air.
PICTORIALLY
One. Never use black paint. The only true black is at the bottom of a mine. Use dark grey at most.
Two. Never use white paint. The only white we perceive is by staring into the sun, which is a bad idea. Use light grey.
Three. In the fifties there was no white paintwork in industrial terraces. (Only the very posh painted their houses white, because they could afford regular re-paints. It was also a consequence of pigment. White lead (very dangerous but hardly thought so at the time) was very expensive and was the major, if not the only source of domestic white paint.
Four. Pigments used domestically by the less well-off, were brown, green, maroon, and - if there was a painter in the family the ochre colour of artificially produced oak, using feathered brushes, etc., this was a big show-off! - but unlike white it weathered very well. There was little blue - pigment again - and no, light, pretty colours. There were few black doors, considered funereal by those who hadn't seen number 10 Downing Street, ie, everyone.
In model terms I would neutralise (grey-down) even the colours mentioned. The purples and ultramarines of Hornby terrace doors are nonsense as is all the white paint, especially the stonework unless its modern era, or - a result of the trendy young couple who just moved in - but even in the latter case, its not good in model terms. All these dashing colours started in the sixties when people were earning more and getting their old sash windows replaced, and synthetic pigments were becoming common. I would still neutralise the bright colours, even modern image.
Remember, three feet away from your model is a fair distance in real terms - I can't be bothered to work it out - What you are seeing is, for example, not the colour maroon, but the effect of light bouncing off that surface, plus the massive pollution of industrial steam days, dulling fresh colours in a matter of weeks.
One thing, we see the weathering of steam locos these days, but we rarely see modelled the utter filth and squalor of industrial towns; you had to experience it. The smoke belching from thousands of domestic fires and factory chimneys created local weather effects, almost permanent layers of toxic cloud; Sundays were a little better as it was the Lords day and everyone was entitled to a day off. This is the fifties, remember; post-war Britain was little different from the thirties. But still the domestic fug maintained except at the height of summer, and even then water had
to be heated from back-boilers, other than off the hob. Emersion Heaters were a boon that came, for some, in the late fifties.
Most fifties layouts could benefit from employing a proper artist with an airbrush and mucky colours, to cover the whole damn thing in a dirty tint. Even (especially!) grass greens which are often way too bright.
Final pet hate. Pretty blue skies and fluffy clouds on photographic back-scenes (which I loath, too) They can make a poor model look good, but only in a false way. Rip these backscenes off many layouts and the result would be rather sad.
So, industrial towns were not pretty; nor should a model be.
Tony.
PS: I hadn't seen the above posts when I started! LOL