I have noticed an interesting pattern with the ice cream truck: we always hear it on days when it's poor ice cream weather. We sometimes hear it when it's not, but days like today, when a lovely cold front has rolled through and we get an Extremely Fall day, we *always* hear it.
I conclude that we're a second-tier neighborhood. Places that it frequents every day, people don't buy at all on days like this. But places where we see it less often, people are more likely to buy anyway.