In olden times, it was actually RUDE for a gentleman to speak to a lady to whom he had not been introduced. That is probably not the case here, but ive seen police say on tv that too often people are victimized because they dont want to appear rude. But the people who are mugging them are being VERY rude! So, dont worry about being rude. Worry more about how to ensure your walks are undisturbed - maybe walk in slightly less deserted areas?