1. Unless somebody is pious, he finds very difficult to surrender, because he is sinful. But because of Chaitanya Mahaprabhu, even if someone is sinful but sincere, he can become a Bhakta. Best example is Jagai-Madhai.
2. If somebody does not follow what sad-guru says, then it will be very difficult for him to surrender.
In the land known as Bharatvarsa, even if one is “sarva kama bhakta,” thats a new kind of bhakta. “Sarva kama bhakta” is described as devotee seeking the fulfillment of some material desires, he is freed from all material desires by his association with devotees and ultimately he becomes a pure devotee and returns home, back to Godhead without difficulty.
One who is envious, he can’t be pure.
Due to previous samskaras, one may be expert in some kind of activities, but purity is a different thing.