A polite way to say this.

Unless it directly affected me I would say nothing. How a person chooses to live is their own business. Now, if they were in my house that would be another matter.

I am going to same the same as @snowy22315. If this does not affect me personal I say nothing at all.

Well, when I was ten I noticed my best friend had tons of ear wax in her ears, and it was gross. I thought, well, if I notice, other people will too. So, one day, when she was spending the day with me, I went to the bathroom, and got a few Q-tips, and told her I was going to really quick clean my ears. I offered her a few too, and she took them, and cleaned her ears. The problem was solved, and no one had the chance to make fun of her. If someone had an untidy place, and I felt compelled to say something, which I normally don’t unless I know them well (probably like you do), I might say, oh, did you just have company? But that would have to be an extraordinary situation for me to comment. I’m just so self conscious about my own place. I think it looks fine, but does it to others? Full disclosure: I did once tell my dad his guest toilet needed to be cleaned. He uses his own bathroom so I don’t think he knew. My back hurt or I would have done it. With him, being blunt works best. If they lived with me, I would tell them untidiness made me anxious, so if they could, to please pick up after themselves better. That it wasn’t just them, it was for your own well being. It might not offend them so much.

Hmm... why would how they live matter to me? Am I living with them? If so, then I could clean if they didn't. I wouldn't like it but I'd still do it. If them living like a slob doesn't affect me, then I'd ignore it. It isn't my business.

I would usually say nothing at all. I had a hoarder friend years ago. It got so I had to climb over stuff to get in her house. She asked me to clean but I could not touch her stuff. How whacked out is that?

If I wasn't living with this person, I would say nothing. No one can make me go to their home if I choose not to, unless it's a family member. And if that were the case and I had a family member who had poor hygiene or was living in squalor, I would try to help if I could. Some people are not able at times to do these things--maybe they are in pain, mental or physical, and are just incapable of it for a time. Maybe they don't know it's as bad as it is. If you are not comfortable in their environment, don't enter it. It's hard, I especially get sad to see when people have very poor personal hygiene. It's truly offensive to everyone that they encounter. On the other hand, if they lived with me I would have to say something, that they would have to do their part, practice good hygiene and do basic cleaning.

Unless I know that person well and we are used to being frank with each other I would talk about it but not otherwise

I would just say it

Good question. If I am just briefly visiting, I say nothing. If the person mentions they are sorry but been too busy to clean, I may offer to help some. If someone comes to stay with me, I will tell them to please pick up but will be polite. Like if a plate is left on the table, I may say I am diligent about keeping ants and mice away so please rinse your plate. Right now I'm in my small RV so no room for anyone but next year I have a plan of property and another tiny house.

I just straight up say it. I always tell it like it is. thats the way I was brought up

I suppose it depends on what the situation is. As for being untidy, unless they were living in my home I would say nothing. If it were something that could cause them harm, I would say something in a polite way.

I don't say anything to outsiders if they are dirty. I just move away from them.

@Jenaisle What you said is very polite.

That's polite way of telling off a bad habit.

I would not hate someone for being messy.

If the person was living with me I would start off being polite but if that didn't work I doubt my next comment would be polite

If I am in some body's house then I will say nothing. I am not that person's Mother. I am not the Clean Police. I would not like it if somebody started to clean up what they see as a mess in my house. I might feel the need to tell that person to leave.

It depends on who the person is to me.

I think certain tactful approaches work best. Some ideas would be not to make it personal, be sensitive to that person's feelings, finding the right time to approach the person with your concerns, trying to be understanding as to why they are behaving or acting that way.

I would talk more about my feelings. This would be polite.