Trouble is; if someone pays a lot of money for an old lens, then they see it as a valuable antique and don't mind spending a lot of money on it. But if they pick it up for pennies they see it as an old secondhand lens and are expecting it to fail.
I've a lot of old cameras and lenses and I see Leica Elmars that are badly damaged by idiots who think they can easily be CLA'd without even using the right sized screwdriver and I see the same in the FSU ones. (Sometimes I think they use the breadknife instead if a screwdriver... ) When restored both are good lenses. But because the labour is what you are paying for both cost about the same to work on: people just don't see why they should pay the same for a £3 camera as a £300 one.
Leicas often get neglected as they are/were old fashioned and (2) because people expect them to last forever without any attention...
Both, imo, need overhauling by someone who knows what they are doing and has the right tools and equipment to deal with whatever may be wrong. After all the things can't have spend the last 40, 50, 60 or even 70 years wrapped in cotton wool.
As for the lubrication, I've spent a lot of money on a Leica body having the dried up grease and oil removed and the internal rust dealt with and so on. And I've FSU cameras that cost a pittance (UK £10 or US $15 or so) and which were brilliant.
So it's all a matter of luck.
As for J-8's, my experience of the black one is that it's a nice lens and I use it on the Leica M2 and the Fed 2. You can get a vented lens hood made for Leicas that fits and, of course, will improve things no end. My one is Chinese and the label say "For Leica 40,5mm".
I said "of course" as any lens will be improved with a lens hood and using one without is a good way of spoiling a lot of pictures (but they blame the lens and not their technique).
BTW, whatever you do, don't squirt thin oil into lenses to free the dried up grease because oil can get on the coating and that will destroy the lens.
Also FSU owners have a reputation for selling off their rubbish and homemade repairs, when a proper repair would be a better idea . (There's a lot of repairs that can be done in seconds with the right knowedge and tools but without them you are asking for trouble.)
OK rant over.
Regards, David