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.
Ref >> Srila Prabhupada Vani.