The real answer — no scaremongering
Old deleted data hiding in an Excel pivot table (pivot cache)
Short version: you're probably fine, and you can check in seconds. If you've got a specific file you're worried about, drop it in below — nothing runs, nothing opens.
The short answer
The honest answer is usually reassuring once you know how these files actually work — the danger is narrow and specific, and it's something you can check for directly rather than guess at.
Check before you decide
Drop your file in the box above. It reads the file's internal structure without opening it and without running anything, and tells you exactly what's inside.