Didn't vote but it's because it is not as difficult as he is making it seem to consider the wants and needs of others before acting. This thread as a whole is not condemning advances, it's condemning advances in inappropriate situations. You can greatly reduce your likelihood of making someone uncomfortable with your advances by being empathetic, self-aware, taking note of their body language and applying common sense. It also very weird to me to have to explain this in what I feel is a very 'clinical' way when it should really be intuitive.

Don't approach people in secluded places at night. Don't approach people in places that they cannot leave. For instance, do not approach them in their workplace or an elevator. If an aggressive salesperson started selling to you in an elevator and you were unable to leave it would be irritating, apply unwanted sexual undertones and it is scary. Would you feel comfortable if a salesperson followed you to your car? Would you feel comfortable if they remembered a coffee shop you frequent and tried to 'casually' engage with you there? Would you be comfortable if they waited outside your class/workplace or followed you from your class/workplace to another location? The salesperson analogy gets a bit old but I think it sort of conveys what I mean. These actions are socially inappropriate.

As for recognising body language and social cues, it's not difficult to tell when someone is OPENLY disinterested. If they give monosyllabic replies for the majority of a conversation, they're not interested. If they ignore your questions, try to engage with friends and interrupt you to leave or talk with others, they're not interested. If they keep walking away or turning their whole body away, they're not interested.

It's just like, sometimes you can't get what you want, you know? I get that you see an attractive person and you want to approach them but they are also a person with wants and those wants are equally as important as yours. I don't just mean that sometimes you'll be rejected either, I mean sometimes you won't even be able to approach in the first place. Consider the situation, if it is not appropriate to approach then don't approach. Sometimes it's just not in the stars. There are plenty of appropriate times and places to initiate contact and there are plenty of fish in the sea.