Taiwan's Taipei mayoral campaign is being marred by coordinated online attacks on ordinary people who show support for a candidate, a bad sign for the country's open political culture.

• A century-old Taipei noodle shop invited DPP candidate Puma Shen to sign its wall, which uncovered an old signature from current mayor Chiang Wan-an hidden under a menu.
• Thousands of one-star Google reviews hit the shop within hours, most with no reason given, and the owners repainted the wall and refused interviews.
• The shop had covered the older signature long before the visit, and the paint clearly showed it — the facts did not stop the pile-on.
• A high school student who asked Shen to sign her award certificate was next, turned into a mocking meme circulated in opposition group chats.
• Both sides have passionate fans in Taiwan, and that open support is exactly what people in China and Hong Kong envy — anonymous mobs are eroding it for short-term political gain.

Outlook: Expect more pile-ons as the mayoral race heats up unless candidates publicly rein in their own supporters.