There have been plenty of cases where clergy have dipped their hand in the plate or have organised their own little discretionary account that no-one knows about so they can indulge themselves a little. In fact they've probably used their low salary as a justification. They shouldn't lord it over those entrusted to them, but should lead by example. In the New Testament context, a shepherd walked out in front of the sheep and the sheep followed along behind. That's what Peter has in mind here.
True shepherds show by their lives how the flock is to live.
If you've ever worked under someone like that then you'll know that its a joy to follow their lead. You never feel like it's an imposition, or like they're manipulating you or using you. We talked a few weeks ago about the value of mutual submission in terms of recommending the gospel to others. An attitude of humility is such a rare thing today that people will notice it. That is, we're to let God work on us.