What does 2 Corinthians 12:16 mean?

Among the criticisms of Paul's enemies was that he lacked impressive speech or personality (2 Corinthians 10:10). False teachers, more than happy to promote themselves, were pointing to this to suggest Paul was not a real messenger of God. Another line of attack seems to have been Paul's choice not to take money, for his own use, from the church in Corinth. This issue has been discussed before, but persists (1 Corinthians 9:11–12; 2 Corinthians 11:7–12). Believers in that church seem to have taken this personally, as if Paul is insulting them by serving them without any cost or obligation (2 Corinthians 12:15).

A slander possibly thrown at Paul is that his choice not to take funds from the Corinthians is a trick. The deceiving teachers probably hinted that Paul's real motivation was guilt. They may have implied that Paul was only refusing payment—for now—in order to fool the church into giving him an even greater payment later. Or, so he can steal some of the donation meant to help Christians in Jerusalem (2 Corinthians 8:10–21). This is an absurd claim, as Paul will explain in the next few verses. His conduct, and that of his peers, has been beyond reproach.