Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura has explained ku-viṣaya garta as follows: “Because of the activities of the senses, we become subjected to many sense gratificatory processes and are thus entangled by the laws of material nature. This entanglement is called viṣaya. When the sense gratificatory processes are executed by pious activity, they are called su-viṣaya. The word su means ‘good,’ and viṣaya means ‘sense objects.’ When the sense gratificatory activities are performed under sinful conditions, they are called ku-viṣaya, bad sense enjoyment. In either case, either ku-viṣaya or su-viṣaya, these are material activities. As such, they are compared to stool. In other words, such things are to be avoided. To become free from su-viṣaya and ku-viṣaya, one must engage himself in the transcendental loving service of Kṛṣṇa, the Supreme Personality of Godhead. The activities of devotional service are free from the contamination of material qualities. Therefore, to be free from the reactions of su-viṣaya and ku-viṣaya, one must take to Kṛṣṇa consciousness. In that way, one will save himself from contamination.” In this connection, Śrīla Narottama dāsa Ṭhākura has sung:

karma-kāṇḍa, jñāna-kāṇḍa, kevala viṣera bhāṇḍa
amṛta baliyā yeba khāya
nānā yoni sadā phire, kadarya bhakṣaṇa kare
tāra janma adhaḥ-pāte yāya

Su-viṣaya and ku-viṣaya both fall under the category of karma-kāṇḍa. There is another kāṇḍa (platform of activity), called jñāna-kāṇḍa, or philosophical speculation about the effects of ku-viṣaya and su-viṣaya with the intention to find out the means of deliverance from material entanglement. On the platform of jñāna-kāṇḍa, one may give up the objects of ku-viṣaya and su-viṣaya. But that is not the perfection of life. Perfection is transcendental to both jñāna-kāṇḍa and karma-kāṇḍa; it is on the platform of devotional service. If we do not take to devotional service in Kṛṣṇa consciousness, we have to remain within this material world and endure the repetition of birth and death due to the effects of jñāna-kāṇḍa and karma-kāṇḍa. Therefore Narottama dāsa Ṭhākura says:

nānā yoni sadā phire, kadarya bhakṣaṇa kare
tāra janma adhaḥ-pāte yāya

“One travels throughout various species of life and eats all kinds of nonsense. Thus he spoils his existence.” A man in material existence and attached to ku-viṣaya or su-viṣaya is in the same position as that of a worm in stool. After all, whether it be moist or dry, stool is stool. Similarly, material activities may be either pious or impious, but because they are all material, they are compared to stool. Worms cannot get out of stool by their own endeavor; similarly, those who are overly attached to material existence cannot get out of materialism and suddenly become Kṛṣṇa conscious. Attachment is there. As explained by Prahlāda Mahārāja in Śrīmad-Bhāgavatam (7.5.30):

matir na kṛṣṇe parataḥ svato vā
 mitho ’bhipadyeta gṛha-vratānām
adānta-gobhir viśatāṁ tamisraṁ
 punaḥ-punaś-carvita-carvaṇānām

“Those who have made up their minds to remain in this material world and enjoy sense gratification cannot become Kṛṣṇa conscious. Because of their attachment to material activity, they cannot attain liberation, either by the instructions of superior persons or by their own endeavor or by passing resolutions in big conferences. Because their senses are uncontrolled, they gradually descend to the darkest regions of material existence to repeat the same process of birth and death in desirable or undesirable species of life.”