Candidates running for federal office are required to file quarterly financial reports, and these are available online for inspection. Similarly, pols seeking state office or a judgeship must file campaign finance reports in Harrisburg, and those are eventually accessible over the Internet, too.
But what about candidates seeking local office? Sure, they're required to list their campaign donors and expenses with the local elections office, but who bothers to scrutinize them? Aside from a few reporters and opposing candidates, nobody.