Presumably savvy thieves / vandals would check for them, though I guess they probably also don't want to spend too much time with the signs to avoid getting caught. I will say that personally I find it extremely distasteful to steal campaign signs from someone's yard - so much for the principle of free speech. If you support the other candidate, put up your own sign, don't take mine. But of course rules are for other people.
Of course a politician is going to immediately and publicly blame their opponent. Don't forget "flase flags" are a thing. Although a false flag is probably unlikely in this case, it's interesting how the politician blamed the whole group rather than a single person.
