In all my time collecting, I've only run across one razor that had so much wear it was near unusable. Very few razors are old enough to have that much wear, and 99% of them are three piece razors made before 1920. The vintage twist-to-open razors can have their own issues, but 99% of those come from being dropped, and can usually be fixed with a pair of pliers. The average bloke doesn't need to worry if a used vintage razor works. If that is a concern, you can always buy from the forums.