[ewoodrich]

The preliminary flagging process is done through an automated system that compares your return with others in your income bracket, as well as other characteristics that suggest errors or ommisions. I assume this would be one of many signals that are included. Besides, having your return flagged doesn't mean you will be audited, it just means a human will likely review it and make a determination.

There is no way I could imagine social network posts would be used as the sole or even as a major indicator for an audit. If it was, the audit success rate would be terrible, anyway.