As a general rule, a yard sign is an indication of the sentiment of the individual/neighborhood and not a major factor in influencing whom other people are going to vote for. By contrast, watching someone come into my neighbor’s yard and tearing up signs is a highly polarizing/motivating force for otherwise apathetic or undecided voters.

Of course, if you’re in a neighborhood that’s full of very openly hostile political opponents, it might not be motivating in the way we’d hope. A bit like someone shoving a burning cross in your yard. Its as much a threat of future violence as it is an act of petty vandalism. A guy caught on camera doing this shit is motivating for the neighborhood, certainly. But police inaction when this guy is reported is its own kind of red-flag.