For me, sucking cock isn't only about my own physical pleasure. It's about mind pleasure. Of course a good cock has a nice taste and it feels wonderful when it's pulsating in my mouth, but the main point is the submission, is to know that I am giving pleasure to a man, and that he will give me his cum when he reaches the orgasm. When this moment arrives, I know I did a good job, and my brain gets flooded with serotonin, which gives me physical pleasure.