Public service announcement: "Informational interview" is not code for "sneaky way to get a job interview."
If you ask me for an informational interview and I tell you that my schedule is crammed right now but I'd be happy to answer any questions by email (since I can do that when I find 10 spare minutes at 11 p.m.), the correct response is to thank me and email over your questions. It is not to say nothing and disappear.
If you ask me for an informational interview and I agree to meet with you, you are not supposed to use that time to try to get a job with me. If you would like me to hire you, lying about your reason for meeting with me is not a good start.
If you ask me for an informational interview and I agree to meet with you, you are not supposed to look at me blankly and wait for me to lead the conversation. You are supposed to come prepared with questions about the industry or whatever it is that inspired you to ask for my time in the first place.
Oh, and you're also supposed to arrive on time. And if we meet over coffee, you're expected to offer to pay. I will end up paying, but I expect you to try to, since you asked me to do you this favor. And you're supposed to send a thank-you afterwards.
Please abide by the above, or I am going to stop doing informational interviews entirely.