My personal thoughts on noticeability of homeless populations is that the current iterations of cheap "check out" drug are mostly ones which make you dissociate.
Therefore youre not left really caring about how you're being perceived, so instead of hiding away from society you splay out on the curb like a zombie.
They're not noticeable in that sense. There is just a homeless population where there was not before, and the existing hotspots have spread from a small street to a block or an area. There just seems to be more homeless people. The official statistics in Berlin support that. I have not looked at other cities.
One decade+ member of our small rental community is about to become homeless, on account of the way he chooses to live (messily, against city codes, with multiple yard vehicles, ignoring landlord/inspector).
Two years ago I think he still would have cared, perhaps even tried; but that spark (of life) is just gone.
Therefore youre not left really caring about how you're being perceived, so instead of hiding away from society you splay out on the curb like a zombie.