By the time two individuals reach the point where they're joyously, frantically, gratefully or athletically (or any combination of those qualifiers) sharing bodily fluids, a number of mental, emotional and physical processes have preceded "la chose". (As in - porté, portée sur la chose.)
Example: for a vast majority of men, receiving a blow job from a skilled, gifted and enthusiastic practitioner of the art is a dream come true. However, it matters to most of them whether the person who bestows this pleasure upon them is female or male. Why? It shouldn't be a factor, if sex if purely physical.
The model of an ideal sexual contract would involve explicit consent from both individuals and the only criteria required to ascertain its fulfillment would be the responses to: "Did you come?" and/or "Was it good for you?".
Life is rarely that simple or uncomplicated. Sexual activity means a multitude of things for different people at various points in their lives.
Individuals who withhold information about their gender, their age, their health condition, and a range of factors which could determine whether someone consents to sex with them are acting selfishly, irresponsibly, unethically and in some situations, committing a crime - fraud or sexual assault.
Since most countries overtly or covertly support sexist and gynophobic institutions, whether traditions or religious organizations, women are more likely to be exploited by a sexual predator or opportunistic men.
A few years ago, in order to raise students awareness of the real threat that sexually transmitted infections represented to their reproductive health, a pro-condom campaign was launched in secondary and post-secondary schools by educators. The theme was: "Men lie."
Implicit was the rest of the observation ... "because they want sex and they'll try to get it any way they can." Which is not a fair statement, because not all men will lie about the things that would make a woman think twice or three times about initiating sex or consenting to it.
Knowledge is power. Often childhood survivors of emotional and physical trauma find it difficult to trust, yet may eroticize power imbalance because it is a familiar scenario.
Sharing information creates a level playing field and helps to establish some ground rules. And that foundation can produce some powerfully satisfying interactions, that can be recreative or procreative, carnal or comforting, raunchy or romantic.
Otis Redding sang "Try a little tenderness" - how about trying a little honesty?