Hi Chowder - I'm sure more expert answers will come your way, but my first thoughts are this: I generally know before we even start kissing whether or not I am going to swallow, because as you figured, it's my preferred response so I don't have to think about it. If it's already in my mouth, why not swallow? If there is an issue of STDs, having the semen in my mouth has already exposed me. Maybe swallowing makes it more dangerous, but I figure if my mouth is exposed, swallowing does not make it any worse. (and that is one of the situations that would make me say "no" altogether). The decision I have to make before I begin is whether or not I am going to continue going down on my partner until he ejaculates. If I'm not comfortable enough with him for whatever reason, then I'm unwilling to allow him to cum in my mouth so there is nothing to swallow! Or if he is only good for one "go-round", I am a little greedy and not always willing to forgo how good it feels when he ejaculates inside my vagina. Sometimes I will, because I love the power I have in oral sex, and I do enjoy it and knowing how much my partner enjoys it, but other times I am feeling selfish! This is a thing I really like to discuss with my partner before hand - because one of the deciding factors for me is how he feels about it. I figure out a way, in conversation before oral sex begins, to make sure that he is willing to kiss me on/in the mouth after I swallow. If he has any hesitation or waffles about that at all, then it would be VERY unusual for me to let him cum in my mouth. If it is too "nasty" for his mouth to touch mine after I have swallowed it, then it is too "nasty" for me to allow in my mouth, either, much less swallow! So a lot of it is about his perception of it. I have known guys who do think it is somehow gross, and I would not feel comfortable doing something they think is gross, or too gross for them to be involved with, anyway - sort of like you will use a toilet but not kiss it. Nope - if I get that vibe from them, then I don't want to be that recepticle, and I generally find they are not really good partners for the kind of wet, sloppy, giving and receiving, taking turns sex that I enjoy best. Hope this helps and I'll be looking forward to other responses, too!