
Address validation will not find them
CASS and USPS checks confirm that an address string is deliverable. They cannot tell you that a coordinate sits on a barn, that four houses share one number, or that a real home was never recorded at all.
In a five percent sample of one rural market, one in four records was wrong — duplicated, mislocated, or a structure nobody can buy service at. Thirteen percent were duplicates alone, and four percent of the corrected list had never been on the original.
The FCC's own guidance is blunt about this — matching by address text alone is likely to produce poor and inaccurate results, and location data should be aligned by geographic proximity instead.

