If he cums in my mouth, of course I am going to swallow it. Not swallowing your lovers sperm is disrespectful. I cant imagine a bigger let down than stopping a blowjob right as he is about to orgasm. Girls who disagree, what would you think if your man stopped fucking or eating your pussy right when you came? You would drop him like a bad habit.
Not to mention the mess. I give a blowjob, he cums, I swallow, no muss no fuss. If I stop then he cums all over my hand or his hand or my couch or my dress...shit, I have to go back to work and now I have to wipe this stain off my blouse! No thanks!
After a while, you get used to, and even like the taste.
Plus, it shows respect and adoration of your bull.