If we want to give advice that will insulate people from making a poor networking decision, stick to: "go through the motions for the entire process."
Because the negative reaction from the interviewer isn't to any perceived rudeness in the way you decline. The reaction comes from the fact that you declined at all; the part where you effectively say: "I don't want to work here and no plausible amount of money is going to change my mind."
I have both cut an interview short and I have stayed through an entire interview and then politely declined to discuss an offer.
Even when I went through the entire process up to, but not including the negotiation over compensation, I was still given looks of shock and dismay. I was still treated as if I'd had three heads and told them their baby was ugly. It was essentially the same reaction as when I'd cut an interview short.
So unless you're going to go all the way through the motions, including haggling over an offer and then stringing them along until you have (or fabricate) some other, better opportunity, I don't think it really matters.
Because the negative reaction from the interviewer isn't to any perceived rudeness in the way you decline. The reaction comes from the fact that you declined at all; the part where you effectively say: "I don't want to work here and no plausible amount of money is going to change my mind."
I have both cut an interview short and I have stayed through an entire interview and then politely declined to discuss an offer.
Even when I went through the entire process up to, but not including the negotiation over compensation, I was still given looks of shock and dismay. I was still treated as if I'd had three heads and told them their baby was ugly. It was essentially the same reaction as when I'd cut an interview short.
So unless you're going to go all the way through the motions, including haggling over an offer and then stringing them along until you have (or fabricate) some other, better opportunity, I don't think it really matters.