Alison, you are going overboard (in a kind way!) to ask people if they have fragrances sensitivies! That's something I might do. If your guests don't respond, then you should be free to point out to them that you asked specifically because you cared. If you don't ask, I believe you will find that a small percentage of guests will notice and say something. Truthfully I think those with sensitivities must take responsibility and ask these questions. Its not your responsibility, though your kindness will certainly attract them to your Airbnb!
But I also wanted to share... I am responding as a person with allergies to fragrance—for me, a physical condition. Its not that I don't like perfumes but rather I can't tolerate them. If exposed for more than a few minutes I will most likely have an instant migraine, body ache, fatigue, nausea and any combination of them.
My partner wore fragrance before we met. then quit abruptly. He is highly sensitive to fragrance now. Fragrances contain chemicals, some of which "fix" natural fragrances with chemical compounds to make the scent endure. Canadians studies show that 16% of the population have significant sensitivities to fragrance and its growing.
In our Airbnb, we use our "disadvantage" to our advantage by promoting that we are a fragrance-free environment. We supply scent-free soap, expensive scent-free bodywash, shampoo and conditioner, and laundry soap. One can find fragrance free soaps without palm oil (another story) for almost every product now including fabric softener. You have to smell for yourself, Alison, as sometimes they say "natural fragrance" and this means a naturally sourced scent. Vinegar should be no problem at all. ]
Approx. 20% our guests have mentioned sensitivities. Inevitably, and we are experiencing this right now, some people are accustomed to fragrance and may not fully understand the impact it has on us. Our solution: Say nothing, they will leave soon OR we want to remind you about one of our house rules, one that we are sorry we have. Our guests would never intend to do us harm... we know this so we are kind. When they leave, we open windows for as long as possible, wash sheets 4 times/open air dry, use vinegar and baking soda cleaners only. We have very few guests who wear fragrance. Most don't seem to fully read our rules (probably too long and wordy like this post) or they just don't use scents. Perhaps also here in North America because the use of fragrance is being forbidden in hospitals and offices so people are wearing less.
Alison, I'd say that its great that your guests are sharing information with you in such a kind way. You must be a very welcoming host! All the best to you.