So heres what I've found:
This instant answer is somewhat too specific, I searched for "Python shell" generally, not the EMACS
Python shell. It's not a that bad result, but it's not worthy of being an instant answer.
So this one's definitely off-topic, I serched for Perl scripts not for converting Perl scripts to shell scripts.
This Stackoverflow Question is about two things (or more precisely, about how to combine two things, actually lots of Stackoverflow questions are). This makes it an inapropriate instant answer, too.
These are only some incorrect instant answers from Stackoverflow. I think I've seen more incorrect/off-topic instant answers from Stackexchange than good one's. A way to approch this problem would be only showing instant answers from Stackoverflow when all
the questions tags are in the search term. This way you would get rid of the two-topic answers, which are most of the bad instant answers.