>>31581
On that link there isn't really a definition of unclean.
Wild boars are more clean than those kept at house in pigsty, tho it depends on circumstances, for example they might eat carcass if that's what they have. I think to cannibalism the pigsty kept are the more prone, due to stress related anomalies.
The best are those which are kept on pastures. Like they usually do with mangalica (did nowadays many of them kept at house).