On judging lenses...

Considering the age of these lenses, you can get a lot of sample variation depending on its storage and usage.

Many have internal haze that needs to be cleaned. You might not even notice it right away but it can affect the IQ.

People are hesitant to admit that the lens was kept in a smoky house or one that cooked with a lot of grease.

And it's natural for photographers to unfairly declare a lens "bad" when what it needed was cleaning.

Half of the lenses I got over the past 5 years need a good professional cleaning. I need to get that done one of these days....