meh - I have grown ups asking the scoville units of my sauce too. Every festival, often at farmer's markets.
My response is a very flat and sincere "don't know."
If they press, I'll say, "I haven't had them tested, and since I don't particularly care it's not really worth the expense" - still polite, just not a topic I need to dive into.
It's like when someone asks "how hot is this?" (pointing to a sauce) - same answer. I don't know. I say "to most people it's a medium" - that usually does it, but again, if they press I'll tell them the truth: it's impossible for me to know what they perceive as hot. Warm milk might be spicy to them, whereas I can put a sippy straw in my Black Label.
I label products to what I think the average consumer rating is - and I probably f**k that up anyway. It's all just guesswork.
I wouldn't let it get to you - there are far more significant concerns to deal with in this business.
Kids - that's a whole other subject for different reasons. The obnoxious ones are usually a PITA, but you never know. So it pays to bite your tongue and be polite. At ABQ I had a group of alpha-type teens, came over all blustery and showboaty asking "WHAT'S YOUR HOTTEST SAUCE?!?" - I pointed to the Black and said "that one, now - who wants to try my line of delicious products?"
They tried them all, loved the flavor and the group bought 3-4 bottles between them. I always take the position that I am driving the demo - if a customer wants to take the wheel they can buy their own damn car.
That's actually my gear grinder - when I have 8-9 people sampling sauce (10 was about the biggest group at 1 time over the weekend) & I'm going 1 flavor at a time, describing each sauce, and I get someone in the middle of the group saying "I wanna try THAT one!" and point to a sauce.
I'll just say, "i'm demo-ing for the whole group, so you have a choice - you can either sit out for a min until I get to that one, or you can taste them all along with the rest of these folks."
I had 2 people walk away, clearly too impatient to wait. And good riddance I sez.