A legitimate collection includes a Manifest.txt or Set_List.csv that matches the original release sheet from the designer. Cross-reference set numbers, file counts, and MD5 checksums.
: The phrase may belong to a specific educational curriculum or a "cut and paste" sentence-building activity used in classrooms, where "Polly" is a character name and sets 1–75 represent a progression of difficulty. DD Polly Sets 1 75 Are All Available Here But...
Having a complete list in front of you makes it easy to spot which numbered sets command a premium on the secondary market and which are easy pickups. The Big "But...": What to Look Out For A legitimate collection includes a Manifest