I have celiac disease, which means I can't eat wheat/rye/barley/others- any grain that contains the protein gluten. This isn't an allergy- it's an autoimmune disorder that causes the body's immune system to attack and destroy the villi of the small intestine, without which the body is unable to absorb nutrients into the bloodstream. It takes very little gluten to produce this response- less than a crumb can do it in some cases, and it can make you very, very ill. If left undiagnosed, it can cause malnutrition, anemia, osteoporosis, and cancer.
The only treatment is to stop consuming gluten. This means no bread, pasta, flour tortillas, cookies, pies, cakes, gravies or soups thickened with flour, nothing breaded or batter dipped, etc etc and most processed foods, 'cause it's used as filler or preservatives in so many things you never would dream of.
What this means is that there are many many restaurants that I can't even have a salad in anymore, because they won't keep things segregated from each other, so when I find places that I can trust, I'm thrilled to death. Once I've explained my problem to the manager of that restaurant and my server, I'm putting my intestinal health in their hands.
You would think this would make me very paranoid, and at first, it did. When I was first diagnosed, I weighed about 95 lbs and was too weak to go out much anyway, but it was a very long time before I even tried, because I was terrified of contamination. Over the years, I've been learning to read labels, learning to ask questions, learning that all the things you can have do still out number what you can't and that sometimes, things are going to get ugly no matter what you do because you can't control the world. Life is messy, life is chaos, life is dirt, bacteria, mold, fungi and slime, and life is not gluten-free.
You can make yourself really crazy trying to, or you can roll with the punches, take responsibility for your own life, and realize that risking a dirty spoon in your tea while laughing in your neighbor's messy kitchen with her waffle-crumb encrusted toddler giving you sticky kisses on the mouth is totally worth it. Or not. YMMV.
I don't sweat it anymore- I do the best I can to protect myself, but I'm not going to refuse to eat at someone else's house just because they don't segregate things like I do at mine- I'm just careful not to touch the bread.
Basically, the point I'm making here is that even if your vendor is mixing stuff in their kitchen with kids underfoot- why should that gross you out so much? If your neighbor brings you a plate of x-mas cookies or a loaf of banana bread from their kitchen, would you throw it out because it might be contaminated or because you haven't inspected her kitchen? In my case, I'd give it to my kids, unless it was gluten-free and prepared with me in mind, but still.