Only if the person were saying it because she was fed up with the obvious sexual tension that’d been between us for a long time. Otherwise, no way. Maybe after eight beers or so, a lot of things seem like good ideas at that point…
Hahahaha!!
Er, no, that probably would not work. It hasn’t so far, anyhow. But it has provided great entertainment!
I’ve actually had this happen to me. So far, no, I haven’t taken anyone up on it. However, the guys in question weren’t all that attractive to me and/or I was doing something far more interesting than sex at the time (DON’T proposition me when I’m going for the high score on a video game!)
I’ve also given my phone number to a guy who chatted me up nicely, was pleasant and all, even though he was ugly as sin. We dated for about a year, and he was good company. So, even though I say he was ugly looking, he had an attractive personality, and we enjoyed spending time with each other.
If I was lipreading her, it might look like she said something else.
But one time a lady escort that I was doing a web site for, called me & asked me if I wanted to get shagged. Being that I didn’t know what the word meant at the time, I said no 
Gee. Nobody’s mentioned Tootsie yet. Sigh. No respect for the classics.
If it was my wife, it’d work. Anybody else, hell no. I don’t need to get my knees broken, and my wife doesn’t need the jail time. If I was single, it would work in rough proportion to how well I knew the lady.
It would certainly work if a certain someone said it… 
Anyone else would get laughed at, then ignored.
Sex is always best when you don’t have to ask - when it just happens in the natural course of events.
Years ago when I was booking bands I worked with a certain singer that I had a very good working relationship and a longstanding friendship with to boot. Admittedly there was a more than a little sexual tension between us but we never acted on it beyond appreciative glances.
Then came my birthday one year. We got a little tipsy. He asked if he could give me a birthday kiss. I said yes. Yowsah. He asked if we should just put ourselves out of our misery and have wild animalistic sex RIGHT THAT VERY MINUTE. I said hell yes.
Worked on me 
No way.
How pathetic would that make me?
But then if my wife asked that question… I’d probably have all my clothes off before she took a breath.
As a single 27 year old guy I’d say the answer is ‘probably.’
I hate to be specific but, it really isn’t a proposition.
If the OP phrase is, “I would like to have sex with you”, it’s really just a statement not requiring a response.
Now, if the statement is “Hey, ya wanna fuck?” Then, there’s call for a response.
Now Blalron, I think I know what you’re next question will be…
And I live in Minnesota.
Him: So, ya wanna have sex?
Me: ::thinks about it:: Sure.
Him: Really?
I think I suprised the heck out of him. We were talking and there was a lull in the conversation when the above exchange happened. He could have been kidding for all I know. We’d known each other for awhile and flirted like mad but had never dated or even thought of dating each other and didn’t date afterward either. We stayed friends (hung out more than before even) and never had sex again.