I've seen that too. I have several sisters, and I kind of think one of them might be a mild hoarder. She has one child, 14 yrs old, and she is a SAHM. She has PLENTY of time to work on her house, but she rarely ever does. Her husband works full-time, and if they are going to have company over, does she spend the day cleaning? No, she waits until her husband is home to help her or do it for her (argh!). Almost every room is a disaster. They have some animals, and sometimes the smell is so strong it's hard to breath in there.
So...most everyone else I meet, their house seems a lot cleaner. Another one of my sisters has five kids, and her house gets cluttered very quickly. Her issue seems more that she is overwhelmed with life and can't keep up right now.
I'm prego with #5, and I manage to usually keep the freakin' kitchen clean (it's been my nemesis because it gets messy so fast!). I have to clean it through out the day and often run two loads of dishes. We have a playroom. The kids can make whatever mess they want in there, which we'll clean at the end of the day. They can bring a couple toys out at a time into the other rooms. We clean toys up everyday, usually right before daddy comes home. We'll turn on cleaning music and usually have the house clean within ten minutes.
If someone is going to come over, I am SO embarrassed if it looks cluttered at all. I want it to be very clean. Usually I can clean the whole house (kitchen, sweep/mop, vacuum, clean bathrooms, etc) and have it totally clean within an hour at the most.
I don't spend all my time cleaning, but we do do it regularly through out the day. I think since my kids are home all the time, it's a constant battle to keep it clean. :-) I'm not a clean freak, but I definitely like an organized house and like to present it nicely to people.
I don't usually care what my friend's houses look like. They can be super messy, and it doesn't really bother me. Most of them don't compare to my sister's house! It's obvious they are clean, but very cluttered. My sister's house is dirty. I've tried cleaning her kitchen and front room before, and by the end of the day, it was back to being messy. It makes the effort seem wasted!