Every year or so I like to review all my favorite objects -- plus a few nemesis-objects thrown in for good measure.
Barnard's Galaxy, NGC 6822, is one of my nemesis objects. It's actually surprisingly easy to spot under dark, transparent skies, especially from southerly latitudes. And like most huge, low-surface-brightness objects, it doesn't need much aperture. I've seen it through my 70-mm refractor from Mount Lassen in California, and there are recorded sightings in 7x35 binoculars.
But that's under dark skies. From the backyard of my country home, which I usually rate as Bortle Class 4 on a good night (SQM around 21.3), Barnard's Galaxy is a challenge indeed. It doesn't help that it tops out just 32 degrees above the horizon, down in the light-pollution belt. As I was viewing it last night through my 12.5-inch Dob at 59X, I was reminded of something else I had done some completely other place and time -- I couldn't quite remember. And then it came back to me.
Barnard's Galaxy is to Bortle-4 skies as M33 is to Bortle-8 skies. I can see it -- sorta, kinda. I know there's something there, and can even vaguely make out its orientation and size -- which is huge. But it has no edges, nothing firm to grab hold of. If I look straight at it, it promptly disappears entirely. It's impossible to answer the question "does it extend to point X?" If I think the answer is no, then a further look makes it seem as though point X is in fact a smidge brighter than the sky a little further along. But if I think the answer is yes, then additional inspection make it seem as though point X is just like the rest of the background after all.
Another useful analogy is that Barnard's Galaxy is to M33 as M33 is to M31.
And then, of course, there's the huge, scary world of galaxies with even lower surface brightness than Barnard's. Like IC 1613, which I can barely see even under genuinely dark skies.