When is the doctrine of God's Word unsavory? When it is taught absent personal zeal.
Doctrine without zeal is either like a sword in the hand of a madman, or else it lieth still as cold and without use, or else it serveth for vain and wicked boasting. For we see that some learned men become slothful; other some (which is worse) become ambitious; other some (which is of all the worst) trouble the Church with contention and brawling. Therefore, that doctrine shall be unsavory which is not joined with zeal.An armed lunatic. An impotent craftsman. A wicked braggart. A slothful steward. An ambitious cleric. A contentious churchman.
- John Calvin, Commentary on Acts, 2:154.
Do not despise the zealous preacher... there are many options that are much worse.