DOCs just turn up but you still don't have to allow them access without court orders in place. As for the "I'm not doing anything wrong" thing, maybe your not but too much power in the hands of bureaucrats or even law enforcement is a bad thing. An example of this is my sons Indonesian friend. When they brought in the anti terrorist laws after 9/11 and made it ok for the police, AFP etc to hold people without bail and search houses without a warrant my sons friends uncle and aunty who are market gardener were raided because one of their racist neighbors (who knew full well they were market gardeners) dobbed them in for buying lots of fertiliser. The AFP raided at gunpoint at 5 am. The house was ransacked, the kids were terrified, they were screaming abuse at them and threatening to shoot the husband and oldest son,they took the husband away, he was in custody for 10 days before they even interviewed him and then a further ten days with no charges laid, no access to legal representation and then finally released without charge. When they tried to get some justice they were told that under the Border Security and Anti Terror laws the AFP had done nothing wrong. This is the reason unfettered power can not be given to any government department, too much margin for misuse and misconduct.
Bel I was still typing after you answered Jamies post, haha