There are 3 further distinctions which would resolve this:
A) Since the Talmud says that these people LIVED in the neighborhood of
Rabbi Meir and his wife perhaps she knew them and their wives and knew they
really felt guilty about their behavior. So exception A (to praying for
destruction) is if you know from friends that the person has "leanings" to
repentance then pray for repentance
B) In a similar manner if the person came from an important family-- that
can often be used to encourage their repentance ("You who come from this
family are doing this??")
C) Finally the Talmud says that a person who sins and says he will repent
and then sins again and says he will repent is not allowed to. So it is
conceivable that after you try to get them to repent and they rebuf you you
can pray for their destruction.
Does that sound right? Let us summarize: You know an evil doer: He has no
friends who says he feels guilty, he comes from a "bad family" known for
this type of deed, and those few friends who once thought he would repent
have given up because he never shows any change. Under such circumstances
I think even Rabbi Meir and his wife would agree.
A final thought for support: The great Gersonidees (Ralbag) states: "The
mercy to the wicked is cruelty for the righteous". If these people do NOT
die then the people they persecute will suffer terribly.
I hope these insights help
Russell Jay Hendel; RHendel @ mCs drexel edu;