There will always be bad and even corrupt referees. But personally I don't think that Italy have suffered particularly more than other countries over all their history.
The best way to find out is using modern technology on all available moving pictures of international matches by judging following situations:
1. disallowed goals that should have been allowed.
2. allowed goals that should have been disallowed.
3. referee whistlded for off-side when there was no off-side.
4. referee did not whistle for off-side when there was off-side.
5. giving erroraneously a penalty-kick, corner-kick, free kick close to the penalty box.
6. not giving erroraneously a penalty-kick, corner-kick, free kick close to the penalty box.
On most occasions on 100 wrong decisions 50 would have been in favour and 50 in disadvantage of one country. May be 51-49 or 49-50, but that won't be shocking. If it will be shocking if it will be 60-40 or 40-60, something like that.