But here's the catch; it's the only (or one of the few) source(s) found, and nowhere else.

For instance, it:
1) was uploaded from the source as low-res to start with (say, if it's a very old image),
2) was posted to only social media sites (given their compression), or
3) mirrored/shared to other sites if the original source was deleted.

Is it still acceptable to post that low-res image where no other image source is found?

AlexYorim said:
But here's the catch; it's the only (or one of the few) source(s) found, and nowhere else.

For instance, it:
1) was uploaded from the source as low-res to start with (say, if it's a very old image),
2) was posted to only social media sites (given their compression), or
3) mirrored/shared to other sites if the original source was deleted.

Is it still acceptable to post that low-res image where no other image source is found?

Yes; posting what seems to be the only version available is fine.

The issue comes with people (usually accidentally) uploading low res when a better res version is already available. If the only version available is highly artifacted and low res, then that's unfortunate but that's the way it is, until someone maybe finds the original or perhaps the artist re-releases it or something in full res.

Generally the guidelines are the same for everything, but if post says it's made in 1996 and is bit low res and bit compressed, I usually give it a pass as long as it's not abysmal situation.

Generally speaking just because something is old doesn't give it free pass. If it's below 200px or if there's extremely visual compression, it still has likelyhood of getting deleted as anything else looking like that, new or old.

Mairo said:
Generally the guidelines are the same for everything, but if post says it's made in 1996 and is bit low res and bit compressed, I usually give it a pass as long as it's not abysmal situation.

Generally speaking just because something is old doesn't give it free pass. If it's below 200px or if there's extremely visual compression, it still has likelyhood of getting deleted as anything else looking like that, new or old.

Tru; should've clarified that standards still apply to these old uploads.

I was more or less talking in the context of an image being high quality enough to approve, but obviously artifacted or something. If it fails the usual standards of quality and/or size, it'll be declined, yeah.

There's one artist who gets posted here once in a while that posts art made in the 70's and 80's... poor stuff's been battered and loved over the decades. The art's still pretty good, even if the papers a little wrinkled, and the scan's a bit rough.

We don't wholesale accept things just because they're old, or "vintage furry" or "part of our heritage" -- but we do bend a little bit where reasonable.

tracy_j_butler is a lovely example.

She makes wonderful art now: post #1414432 post #1339837

And she made wonderful art back in 1999 too: post #72228 post #72234 post #72227

though all of those are tiny and fuzzy.

(on a side note, when I was a little yerfling, I wanted to draw like her SO MUCH.)