"It's okay if you're attractive enough" is wrong on multiple levels no matter how it's phrased.

Maybe the best way to phrase this is "If there is mutual attraction." Plenty of people marry their co workers. And there are plenty of non creepy/harassing ways to figure out if someone else is interested.

That's a bit of a different scenario, though. The statement I objected to is sexist in at least one of these two ways: 1) it presumes that women appreciate these advances from men in positions of power simply because they're attractive (i.e. that harrassment is "forgiven by default" if it's done by an attractive guy) or, 2) women are vacuous and easily charmed by attractive men to the point where they don't recognize sexual harassment for what it is.

It probably isn't sexist to say that people appreciate advances from someone who is extremely attractive, as long as both are available and looking.

The problem is that it's inappropriate to express interest if you're in a position of power over someone, whether you're a man or a woman. I think you were saying that, but point #1 lacks that context.

That's fair, and I edited my comment to reflect that.

Are there? Please explain them to me. I'm serious and want to learn

(Assuming no supervisory relationship or other power imbalance,)

Make an introduction. Make your mild/budding interest in them clear enough. Ask them to do something that's clearly not work with you.

"Hey, want to get coffee sometime this weekend?"

You'll find out if there's preliminary interest or not. If they're interested but busy, they'll figure out how to make that distinction clear. If "sorry; I'm busy" is the entire answer, just assume they're not interested. You get one "free" chance here; make it fairly clear that you're interested; don't invite them out for a "team dinner" and then arrange for the rest of the team to not show up or other chicanery.

Unfortunately, it's not quite that easy. Sometimes it's not clear that you're asking them on a date. Ex. I've asked a professional associate out for drinks. I thought it was a date, she didn't, and she was offended when I tried to flirt a little. (I stopped once I realized she wasn't interested, but it could have been offensive.)

Personally, I've stopped ever pursuing anyone who works in the same industry due to the potential for weird dynamics, but it's sometimes not as cut-and-dry as people make it sound. Like the example with Chris Sacca, is flirting with someone at a conference a form of sexual harassment?

That chicanery happens when the man is insecure and thinks a woman won't go out with him unless it's a team dinner. If there's a magic potion to turn an insecure man to become more secure without the man doing stupid things and screwing up asking out women, you'd make trillions.

I'm not saying what sokoloff said is wrong (or doesn't work) but I'd not invite a woman (or a person) to coffee before getting a physical approval. This physical approval (eye contact + smile) is usually a certain indicator of interest. I'm talking about same level co-worker.

I'd not go with a co-worker that I have power on (like being the direct manager, or the VC). I can see many ways where the relationship can go awfully wrong.

How do you get physical approval without flirting?

I have eye contact and smiling with lots of people. It's just being friendly.