I have a half dozen OM 50/1,8's and two are so hazy inside they definitely suffer.

The latest versions ("Japan" & "Made in Japan") have some funky sealed front lens setup that can't come apart - making cleaning impossible. (unless there is a secret way to open them?)

While I prefer the silver nose and earliest MC versions, I do have a pristine 1.8 MIJ that I haven't even tried yet.