Person I knew a long time ago wants us to give her son a bit of a holiday - would you?

I would have guessed they were American. It seems quite a normal thing to do for them. We've met several Americans while on holiday in other countries, often only chatting to them for an hour or two in a bar, and they almost always give us their details and say that we must stay with them if we are ever visiting their area. And they genuinely seemed to mean it. My parents met an American man while on holiday in Switzerland, and he invited himself over to stay with them for a few days, and, to my surprise, they agreed and he came to stay.

I get why you don't want to host him, and I probably wouldn't do it either. But I don't think it's particularly cheeky, it's just a cultural difference

I would have guessed they were American. It seems quite a normal thing to do for them. We've met several Americans while on holiday in other countries, often only chatting to them for an hour or two in a bar, and they almost always give us their details and say that we must stay with them if we are ever visiting their area. And they genuinely seemed to mean it. My parents met an American man while on holiday in Switzerland, and he invited himself over to stay with them for a few days, and, to my surprise, they agreed and he came to stay.

I get why you don't want to host him, and I probably wouldn't do it either. But I don't think it's particularly cheeky, it's just a cultural difference

Yes, we have hosted a number of young people over the years. We live somewhere where people pay a small fortune to come for a holiday and if people are travelling round or doing a gap year we can usually accommodate them for a couple of nights. I echo what @mondaytosunday says. When I was young several people very kindly put me up when I was travelling around and it's good to feel I can offer something in return. And I learn things from the youngsters.

My concern would be that you sound disapproving and affronted, OP. It sounds as if you don't generally host. All those years and you are still full of resentment and disdain for your former friend. I'd love to hear her pov about how your relationship foundered. So if you can't park that negativity, say no to the son.

And my advice to anyone offering accommodation is to be really clear about date of arrival and departure. 'You can stay for three nights, from Friday night through to Monday morning. I can take you to the station for between 9 and 10am on Monday morning.' I've been caught out by a couple of Australian guests who asked to stay for a couple of nights and then dug in for a couple of weeks.

I haven't replied. I'm not sure I intend to. I find it so fucking rude.

Culture is I'm a Brit and they are American.

I think it's changed. It was more common in the 80s when travel was more expensive. Now we have Travelodges, Premier Inns and AirBNBs everywhere, cheaper flights. Plus people are less likely to have a guest room. The second bedroom in my parents' house was always the guest room - children were in the single bedrooms and further down the pecking order.

I’m a big believer in altruism , we actually did host a teenager on their gap year through a loose connection and a week turned into a 2 months....
It probably wasn’t the teenagers fault (they were 18) but they just had zero awareness about offering help or a couple of quid for food and board etc and expected lifts etc , I think it was just total lack of awareness which is probably normal for some at that age.
I’m patient and very much into helping people out in life where I can but I’m also someone who has had a very difficult background and had to drag myself up and deal with a lot of stuff alone from around 16 so I found it a lot more difficult than I thought I would to deal with the selfishness and lack of awareness……
I also was 31 with 3 very small kids so probably wasn’t the best time to host , I’ve been given zero support all my own life .
There are serious CFs in the world , for some of my inlaws it’s a lifestyle choice , constantly asking to stay in people’s houses for their holidays, constantly looking for freebies, they ask directly putting people in very awkward situations. The only way to deal with them is directly. My sil actually said “oh we’ll send dc to you as he can learn ether language and enjoy learning about the culture we live in once he’s 15 “. She was literally acting as though it was a statement, not a request. I simply said , “nope , we have our own three teens and don’t want to host another and have extra responsibility”. The arrogance… almost like she was saying it in a “he’d love to go to you and you’d love it 😂😂😂😂

I’m a big believer in altruism , we actually did host a teenager on their gap year through a loose connection and a week turned into a 2 months....
It probably wasn’t the teenagers fault (they were 18) but they just had zero awareness about offering help or a couple of quid for food and board etc and expected lifts etc , I think it was just total lack of awareness which is probably normal for some at that age.
I’m patient and very much into helping people out in life where I can but I’m also someone who has had a very difficult background and had to drag myself up and deal with a lot of stuff alone from around 16 so I found it a lot more difficult than I thought I would to deal with the selfishness and lack of awareness……
I also was 31 with 3 very small kids so probably wasn’t the best time to host , I’ve been given zero support all my own life .
There are serious CFs in the world , for some of my inlaws it’s a lifestyle choice , constantly asking to stay in people’s houses for their holidays, constantly looking for freebies, they ask directly putting people in very awkward situations. The only way to deal with them is directly. My sil actually said “oh we’ll send dc to you as he can learn ether language and enjoy learning about the culture we live in once he’s 15 “. She was literally acting as though it was a statement, not a request. I simply said , “nope , we have our own three teens and don’t want to host another and have extra responsibility”. The arrogance… almost like she was saying it in a “he’d love to go to you and you’d love it 😂😂😂😂

I would reply with “Sorry, who is that?” And when they reply, messages back again with “Think you have the wrong number”.

I will go against the trend. It's frequently done in my circle. Have done it often for old friends, friends of friends, distant relatives we'd never met.
Have been welcomed likewise.

Have often been asked to find families to host young people in the summer, although it's increasingly difficult.

It feels such a sad, self-centred world we live in.

Well now. My parents moved to America and as their friends from England and Ireland had kids reaching 18 the summer before uni or taking a gap year and we were hit with several requests to put them up, sometimes for a few weeks. These would also be from friends of friends or distant cousins - people my parents may have had a very tenuous connection with.
But you know what? They usually said yes. Because they could remember venturing out at 18, thinking they knew everything but finding out actually the world can be big and lonely and a bit scary. Finding a friendly port in this storm was great. A few hot meals, a tour of the area, some words of encouragement and off the young person went, confidence somewhat restored and with the knowledge they’d made a connection.
So please do help out this young person and give them an introduction to your area. Show them a few sights, introduce them to people their age if you can, encourage them to get out on their own to explore. I bet years down the line they will remember your kindness and generosity and hopefully offer the same to the next generation.