I have learned that you just can't call someone and expect them to spill their guts. You have to plan your strategy, rehearse it in advance in your mind, and then tailor it to the person you are likely to be speaking with. It will be different if you are talking to an expert, where it helps to have a good command of the jargon, rather than just an ordinary worker for whom a job is just a job. To give you an idea, this morning, when I called Mack's, I said to the gal who answered the phone that I lived in Texas and might at some point want to try their pizza on a future visit north but wanted to know more about their pizzas. After we got the pizza size issue out of the way, which was a softball question for which I believed I already knew the answer (which she confirmed), I mentioned that I had a lactose intolerance to mozzarella cheese. I don't know if she knew what lactose intolerance is but that compelled her to tell me that they didn't use mozzarella cheese, only white cheddar cheese. That opened up a discussion of the type of cheddar cheese (i.e., mild versus sharp). When I "attacked" their pizza as being overly greasy/oily based on what I had heard, that put her on the defensive and prompted her to explain that the fat was from the cheese and was quite normal. When I speculated that it might be oil used in the sauce, she said that they did not use any oil in the sauce. Although I asked about the type of flour, hoping I would get really lucky, I knew from past experience that workers rarely know the answer to that type of question.
BTW, I called Mack's before they would get very busy and either wouldn't answer the phone or cut the conversation short.