Is string theory really science?
I think string theory should be regarded as a framework or paradigm, not as a single theory (alas the name!). In that sense it could be compared to quantum field theory, which is also a paradigm. A better name for String Theory would perhaps be "string paradigm".
In that sense you can wonder what it means to "falsify string theory". You should be able to falsify specific theories in the string paradigm, but to falsify the paradigm itself would be very hard. How would one for instance "falsify the framework of quantum fields"?