To expect them to “ask” first?

Don't be ridiculous.
There is no reason why my adult son couldn't ask a friend, or friends home because he has a younger sibling.
What an odd way of thinking you have.

If you would let your some know if you had invited people to the house, then he should do the same, but I don't really see a problem if they weren't being really raucous and disturbing you. But Why would you be embarrassed at someone seeing you in a onesie?

I don’t think they’ve done anything wrong except been a bit thoughtless

if it’s never been discussed then he’s just not thought and presumed

I wouldn’t make a big deal I just tell him to message in future

This. What on earth was he thinking?

Sorry but he's not the homeowner. He should always plan ahead and ask before hosting.

This. If he wants to do this kind of thing, he should get his own place. It shows a lack of awareness and a lack of respect to you too. You shouldn't be placed in this kind of situation in your own home.

Of course he should have asked out of respect to you, his mother.

Adult DD will always let me know if she's bringing her boyfriend or a friend home. No rules on who or when, as long as I know they're there, and there's no noise after 9pm.

I don't think rent has anything to do with it, they aren't housemates, it's the OP's house and she can set the rules.

I would not be ok with late night/overnight guests without previous discussion

I don't see the relevance of whether he is paying commercial rent, or housekeeping, or nothing at all whilst saving to move out. It is his home, the same as the OP's.

I wouldn't expect my (adult) dc to necessarily forewarn me of bringing someone round, as, once undressed, I'd be upstairs and not going to bump into them anyway. Same as if I asked someone back when my dc were home.

I do think though, that everyone living n a house with other people needs to be considerate of making noise in the house when they are aware others are trying to sleep. That is the part that I would be annoyed about.

YANBU, he should give you a heads up.

But in terms of embarrassment...if I were a grown man who accidentally went back to a colleagues house at 1am for a gaming session, I feel like I would be WAY more embarrassed than the colleague .

I don’t think anybody should be keeping anyone else awake in a house. My children both lived at home for a very short while after Uni. They would not have brought anyone home after our bed time.

I don’t think it matters whether he pays rent or not, it’s common courtesy to let you know.

When I flat shared with my best friend through our 20s, we’d always let each other know if we were having someone round for tea or whatever. Or if bringing a guy home after a night out we’d send a text just as a bit of a heads up etc.

I do think the issue of him bringing people round in the middle of the night and keeping you awake gaming needs to be addressed, that’s not on.

Someone who lives in someone else’s home is a lodger not a tenant and therefore do not have the same rights as a tenant.

Adult children are different again because they seldom pay a deposit, market rent, full share of all bills and all their own groceries. They get less rights than a fully paid up lodger even though many think that is “so unfair”

The three of them were thoughtless. If the friends know you from work it should’ve crossed their minds that a colleague might not want them turning up late at night. Your son should at least give you warning when there will be other people in the house.

i think you need to re read the post, OP literally said it kept her awake

rent is irrelevant here, common courtesy to just let you know isn't it, I don't mind people being in my house as long as I'm told just so that I'm aware

my mum always used to bring her new bf round without letting me know before when i lived with her, id be making dinner or in my pyjamas half the time and was uncomfortable with surprise guests coming in seeing me and making comments had to say to her i didnt mind him being there obvs but please just give me a heads up!!!

I think it's incredibly disrespectful of your son. It's time he moved out if he wants to behave like that. It's even worse that they are clients but in any case I wouldn't want random men turning up in the middle of the night. Your son needs his own place.

But it obviously didn't keep the OP awake - quite the opposite. If she'd been awoken by their noise she wouldn't have been surprised to see them after she went to the loo.

But if he'd messaged you wouldn't have got it on account of being asleep? I do think in general he should give you a heads up about guests but in this case I also see why he'd have erred on the side of not waking you up.

I wouldn't have been especially embarrassed in a onesie though!

Omg you've just reminded me . . . I actually did that once, went for a late night wee, walked out starkers and my housemate and his mate had come back and were in the room opposite the bathroom, his mate got an absolute eyefull, i hastily retreated to my room in a cold sweat!

Op, YANBU. I would hate to bump into anyone like that, it's actually rather scary suddenly seeing men in your house that you didn't know were there.

You could have come out of the loo in your birthday suit!!