I completely agree that generally you get what you pay for. However, I've been pretty lucky. I spotted my bar in the spindle and it had good contact all around. The last inch or so at the tailstock end doesn't seem very good, but until I get the tailstock properly aligned it's hard to tell. In the meantime I just don't use the last inch or so. Similarly I found <0.0001" TIR on both a backplate mount ER32 chuck and an MT 2 version of Chinese origin. The collets are another story. The ones I've measured have 0.0005" TIR.
It's going to be really interesting to test my Clausing 4902 with there MT 4 bar I bought. It's a plain bearing machine. I know from my level that the center part of the bed is worn down about 0.003" but I never had a good way to test the straightness of the prism or the headstock alignment.
My first project on it was a bar with a series of collars at 1" spacing which I attempted to turn separately to a tenth. It taught me a hard lesson about thermal expansion and the need for flood coolant. I hope to succeed in a rematch.
My first lathe was a Sears 109 which is a miniature 1880's machine. I still have it for the simple reason it was more trouble to sell than it's worth. But I'm beginning to develop a perverse fascination with trying to make some tight fit parts on it using nothing but spring calipers. The main job I did on it was rebush the leadscrew. That came off well, but I feel as if I cheated by using modern measuring tools.
I enjoy doing old school bench work with files and can readily hit parallel and square on 2" x 4" plates of 16 gauge steel to a thou using spring calipers and a square. For lots of work I can do it with files faster than I can set up the mill. So trying my hand at late 19th century machining seems an interesting way to spend an afternoon. Modern machines were built by people using such machines and methods. I admire skill in any domain and have spent my entire life trying to learn as many as I could. The fly in the ointment though is that they are transient and I have learned the hard way that things I was very proficient at 30 years ago I can no longer do without significant refresher practice.
120 years ago if a ship broke down at sea everyone died if the engineer couldn't fix it. So a marine engineering school exercise back then was to take a round bar and flat plate, file the bar hexagonal and make a hex hole in the plate so that the bar was a close sliding fit in all 6 positions for the length of the bar. I still haven't worked up the courage for that. But maybe some day.
@michiganbuck I followed the same practice on VWs, but I follow the factory manual on my Toyota pickup which uses friction as the spec. After today's exercise I'm likely to play around with a scrap spindle and housing to get a better feel for how the end play and friction methods relate. I suspect that the change is more related to the demands of factory production than anything else.