I think this is a loaded topic and oneh that needs to be handled carefully. Of course we welcome guests of any age and have had lovely people from every demographic. Our place is sometimes used as an event space and we started that ong before we tried Airbnb. These are some observations from interaction with older guests both when we host events and host guests who stay for vacations.
1. If you look 'young", there can be a level of distrust that you are not qualified to help them. I have found this to be true with certain older men in particular. You have to work extra hard to convince them that you are professional. With household issues sometimes I gave felt as though they wanted me to acknowledge that they were more of an expert on my home and yard than I was. And comparisons to their children can be difficult to hear.
2. There's a fundamental misunderstanding about what an Airbnb is/offers. As one might complain about a hotel room in order to be switched, so might an older guest be used to complaining for fee credits, extra consideration, etc not realizing that's not the norm. It's a new form of hospitality and they just might not be as savvy.
3. Ratings are seen as a "grade" and typically pretty low. The "no one gets 100%" mentality is very common among my older guests.
4. Value is very subjective. We are underpriced for our market but I have had older guests complain about our nightly charge even when we were at $50 a night starting out (entire house with lots of goodies for guest.) No one under a certain age has complained. When we do events we have very reasonably priced packages. It's only ever a parent of a bride or groom who balks and says "HOW much are you spending??" even when they are not paying our fees.
We always try to put out as much kindness as we can and talk about our love for our cottage. Because we do love it. Bringing that back into the conversation reminds our guests we are not just out to scam or take their money. We stay at our space as often as we can and know it quite well. We respond quickly and thank them for their info. We couch things with "that's really interesting! We hadn't heard that before. Is it bothering you? Tell me more about it." Sometimes it's hard to basically be told you can't possibly know what's going on because you haven't been on Earth long enough (FWIW we are in our late 30s so not babies) but you just grin and change the topic.