Final answer:
The defendant's best defense is that the contract was contingent upon the defendant's personal satisfaction with the final product, a subjective standard that is legitimate under the law as long as the dissatisfaction is genuine and not arbitrary.
Step-by-step explanation:
The defendant's best defense in an action by the plaintiff for non-acceptance of the wooden door with the coat of arms would be that the agreement itself provided for a conditional obligation based on the defendant's satisfaction. In such cases, courts typically view this subjective standard of personal satisfaction as a legitimate defense, so long as the dissatisfaction is genuine and not capricious. Since the agreement explicitly stated that the defendant would be under no obligation if not completely satisfied, the defendant can argue that they have the right to refuse the product regardless of its quality or the effort applied by the plaintiff, as long as the dissatisfaction is honest and in good faith.
It is important to note that such subjective satisfaction standards in contracts can lead to disputes if the seller believes that the buyer is using this clause to escape the contract unfairly. However, the defense would focus on the specific terms of the agreement, emphasizing that the standard for completion of the contract was the defendant's actual satisfaction, not simply expert craftsmanship or adherence to the agreed design.