That's the trouble - how do you know that a "used" chip hasn't been damaged?

Some types of damage can just cause certain parameters to become marginal - so it might appear to work most of the time, but give you very peculiar effects at other times.

Such situations can really tax your diagnostic skills!

So, as Richard says, try it if you want; but don't rely on it being a cheap alternative to buying new chips - especially in terms of your time.

The same would apply to other chips - not just 8052s...