What can I say?
People look at every individual aspect of their regional slum (sidewalks, density, transit, mixed uses, brick facades) and assume that each of these elements can individually cause decay in their neighborhoods. How can sidewalks draw undesirables? Where will they draw them from? They'll only be a few feet closer to your house which is setback at least 20 feet. Its not even private property!
There are some towns I could never work for because the residents would cause me to exibit uncontrollable rage. (Should I say that during job interviews?)