While period originals were 'good' - they're nowhere like a set of today's military M-19's, or M-22's.
The lens technology just wasn't there, but it was pretty adequate, all in all.
Originals can be disassembled and the lenses cleaned by you - they really don't require a specialist, so long as you work slowly and carefully, and some of the French-made WWI binoculars lend themselves admirably to this effort.
Best to find a pair that you can look at, handle and glass an area before you buy to see if they give you the needed clarity.
Vaya,
Scouts Out!