1 Corinthians 9:18

What is my reward then? Verily that, when I preach the gospel, I may make the gospel of Christ without charge, that I abuse not my power in the gospel (KJV)

Then: Corinthians understand what he is saying about his reward, that it is the preaching of the gospel itself and he delights in the spiritual harvest. The final phrase here is another caveat that follows from his not taking money. The negative action ensures that he is not abusing the power. The only one expecting his services is Christ (Fee, p. 415). Baker marks two things. Paul is asserting the right not to be paid, and he could boast in the Lord that was the one quality about his work in which he could take pride. It was a Paul thing; not a ministry prescription.

Now: The abuse of power in preaching the gospel is usually cited in another realm - that of radio and tv broadcasting. Many scoffers expect scandals and misuse of the those with a powerful tv presence or personality. When proved true for one, they say it is true for all. Dobson's approach is that of being accountable to a board. That answer works for him, but everyone needs some method by which the ministry stays sensitive to even inadvertent abuse of the gospel.

Extra source: Cornerstone Biblical Commentary 1Corinthians (William Baker), 2 Corinthians (Ralph Martin & Carl Toney), ed. by Philip Comfort. Carol Stream: Tyndale House Publishers, c2006.
The First Epistle to the Corinthians by Gordon D. Fee (Eerdman's 1987) online at http://books.google.com/books?id=XlBp10nUTXAC&dq=Gordon+Fee+Bible+commentator&printsec=frontcover&source=in&hl=en&ei=SwLNSu3nA4v6Mf2XlDo&sa=X&oi=book_result&ct=result&resnum=12#v=onepage&q=&f=false