I don't believe everyone that purchases a low mintage coin with problems do so because they don't know better ..
Some people can live with a problem coin and some can't ...
At the end of the day there just isn't a easy way to determine the value of a problem coin as these problems will vary from coin to coin....
What can you do other than try to see what similar coins have realized at auction ...
Whether it's a inexperienced new collector or seasoned collector of many years buying these coins, that's really doesn't Matter ...
I've always been told that a coin is worth what someone is willing to pay ...