[cookiecaper]

It's ethical because it's a public internet. The same way you can't use the force of law to stop a homeless guy from asking you for change as you walk along a public street, you can't [shouldn't be able to] use force of law to stop a client from asking your server for data as it sits connected to a public network.

It's not unethical for a beggar to continue asking for change. It's up to the passerbys to choose whether or not they'll honor his request, but he is free to make it as long as he doesn't get out of control. Many people see the client-server relationship that exists online similarly. As the beggar can't receive anything that the giver doesn't willingly give, neither can the client receive anything the server doesn't willingly give.

It wouldn't make any sense if a guy could give the beggar change and then sue him and say that he shouldn't have gotten change because he actually wanted to use it for his lunch. The judge would say, "Well, why did you give it away? You can't just change your mind and then sue someone over it." This is also what judges should ask servers who dispense information to clients and then try to take it back.

tl;dr there's no harm in asking for data, even after someone has told you no, as long as you do so reasonably.

[emodendroket]

Strictly speaking there are a lot of places where panhandling is not legal.