That’s not a correct assumption - you likely won’t ever see a pure clear sky like that only by looking at a local METAR report. CAVOK also means “Ceiling and Visibility OK” and not “clear skies” 
In more detail it means:
- Visibility of 10 km or more, and the lowest visibility is not reported ← so a visibility of 11km would already be CAVOK, on the “clear sky” preset is like 200km
- No cloud operational significance ← so no overcast of 2000ft in height but some cumulus clouds might be totally fine
- No weather of significance to aviation ← no hailstorms. no intense showers, but some light rain may still be acceptable
(CAVOK - Glossary of Meteorology)
Still this definition is pretty rough, just like METAR in general is.
Also if the report is half an hour (or even a full hour) old weather might has changed, just as said before
Edit: meteoblue (the second source of relevant data) shows that there are few clouds in the area of Rome:
