I fully agree with your advice. Better buy a fully functional equipment in the first place, than have it serviced afterwards.
It would be a loss 90% of the times.
Buying defective items (at bargain prices!) makes sense only if you can repair them on your own.
That's my experience, for what it's worth...
From the quote above, i get that you had a lens element permanently damaged by lubricant outgassing.
Are you sure?
I have more than 150 large format vintage lenses (2/3 are in barrel), and i've never seen such a thing.
Maybe the culprit is the grease used in focusing barrels, which is not present in LF lenses, but i wouldn't take it for granted.
I've owned my share of old 35mm lenses (including many LTM ones... i've just sold a nice Russar 20mm in chrome), and i never found an hazy lens which was uncleanable.
Most of the times it was just haze coming from polymerized lubricants, which free volatile substances over time.
Sometimes the glasses were left dirty for long time, in a humid environment, so that some spores could start a fungal growth.
One time the front glass of a Roussel lens was completely covered by a thick layer of what looked like hardened tree resin.
ALL of them were successfully cleaned, with no outside help.
That's why i am very curious about your experience.
AFAIK the only glasses that were subject to glazing, or other physical degradation, where the early, unstable "new glasses" made before the end of the XIX century (very few made by Schott, most made by french or british glass foundries). Very soon the unstable ones were retired, and new ones with better specs were made available.
Then there is the yellowing of glasses containing thorium... but that's another story.
You reported something i am not aware of. So i would be happy to learn something more about it.
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