People who just don't bother to clear their walks of snow. I don't want to pick on elderly homeowners, but there are sidewalks in our neighborhood which are chronically ignored, and I know some of them are occupied by people in condition to do it. I'm 41, neither big nor particularly strong, and I spent a lot of my day off today moving snow and chopping ice. If I can do it, most able bodied adults can do it. I also reserve some scorn for people who clear their sidewalks up to the curb cut and then stop. You live on a corner lot, the curb cuts are your job too. Yes, it sucks - I can attest to that since we have lived on a corner lot since 1993 - but we've made sure to keep ours clear. Making pedestrians climb over boulders at the end of your sidewalk is unkind, and frequently unsafe. I had to type this today, before my ice chopping muscles seize up and prevent me from typing at all.