Not answered the poll, as there are too many variables involved. However, I'm not adverse to sex in books and other media, so it's not the sex as such that would deter me from reading on - however, the quality of the writing would come into question there, plus the reason for the scene. Does it lead me to think this is just going to be sex, trivial plot, more sex, trivial space battle, more sex - or does it lead me to think this is a well-written book that is not going to shy away from any aspect of the human condition?
Don't really read sci fi for titillation (I can read other things for that - and isn't "titillation" such a great word btw?) so for me to want to continue reading on, it's going to have to lead me to think the author has more in mind.
Iain Banks, for example, doesn't shy away from sex, and it may not be "central" to the plot, but it's there because, in real life with real people, it's there. Even if you are in an SF or Fantasy setting, we still want people (and aliens) we can relate to, and to be honest, sex is one of the greatest motivators for us as individuals. Unlike the need to own a nicer sofa, the need for sex is programmed in, hardwired in a way that so many of our "moires of society" are not.
Hope this helps!