What is an address? covered the data model. This article goes the other way: a tour of address shapes that consistently break parsers and resolvers, with concrete examples for each. If you are building or evaluating a geocoder, this is the failure-mode catalogue worth keeping next to your test suite.
The falsehoods
This article series is inspired by and cites Michael Tandy's excellent, exhaustive original — the canonical catalogue of address falsehoods, maintained since 2013. Tandy's article is a taxonomy of assumptions that break parsers, validators, and databases. This series expands on that taxonomy, adding historical context on how geocoders have handled (or failed to handle) each category, and what Mailwoman's neural approach changes.
Users do not type addresses the way gazetteers store them. They type what they know, in the order they think of it, with the spellings their keyboard supports, trusting autocomplete suggestions they didn't verify. A parser that only handles well-formed addresses fails on real input.