No country wants/needs to import rapists/gang members/murderers. They have enough of their own. But what's wrong with welcoming GOOD PEOPLE?

How can one tell "good" people from "bad" people?  It's not like they wear name badges ("HELLO: I'm a rapist").
Should we just take their word for it?   Does having a child automatically make one "good"?  Are only "good" people allowed to procreate?

Very few countries want to turn away "good" people.  The problem is telling them apart from the "bad" people.  Not many people bring their rap sheet with them when they try to cross a border.  Nor are they going to confess their "sins" to the border patrol.

While your question is valid, there's not an easy answer to it.   This is the issue Trump was trying to address - we don't want "bad" people in our country.  Unfortunately, his answer was to build a wall across the southern border then deny entrance to everyone - especially those from "selected" countries.  That answer isn't working. 

Are all "  insert ethnicity here   " people bad?    Are all American people good?  Can you tell from just looking at them?  How do we keep the bad people out while welcoming the good ones with open arms?