From people who can read Polish newspapers..
Either they are exaggerating, or they read tabloids.
Don't worry about being kidnapped, if people know your from overseas you will be a sure target of being robbed...
target?? :) I don't think it's that bad.
Just try to avoid dark alleys, don't show people how much money do you have, follow your instinct when it comes for strangers and everything should be alright. I don't think polish cities are more dangerous for tourists than lets say American ones.