Unfortunately for any aspirations you might have for some intergalactic boning, real aliens are unlikely to appear as anything you'd be remotely interested in grinding hips with, assuming they even have hips, instead of flangeblatts or something.
"Great! Now unsheathe your penis horns while I excrete the lubricating acid."
In fact, ignore aliens for a moment and think about the creatures on Earth that have advanced intelligence independent of the human family tree. We're talking things like dolphins, dogs, octopuses, and birds -- animals that look absolutely nothing alike, much less like us. And that's just Earth. Intelligent creatures evolving elsewhere in the galaxy could look like absolutely anything, and the one thing we can almost certainly rule out is that they'll be sexy.
Why? Because what we find sexy is what our species evolved to find sexy. You (probably) don't get turned on when you see a hippo violently evacuate its bowels, but for a lady hippo, that's the equivalent of a Channing Tatum lap dance. We are, for example, the only species on Earth whose females develop large breasts. That happens for no real reason other than that it's the specific switch our evolution decided should activate the boner machine. It doesn't matter how human it may seem; a chimpanzee finds Scarlett Johansson no more sexy than she finds it, which is probably "not very much." Hey, we don't know what ScarJo is into, and we don't want to presume.
And if the aliens look like her? Run.