Well, our house is often a bit of a tip. I don't feel smug about it at all. In fact I can't stand it. I'd love a clean and tidy house 99% of the time, instead of 10%. But I really do spend hours of free time doing stuff with DC that makes a horrendous mess.
We get out chemistry sets, we grow herbs and tomatoes and cacti and bonsais in pots on every window sill, we cook and bake, we do loads of painting, we go out cycling or on nature walks and come back with muddy shoes and baskets of blackberries, we have several pets who shed fur, we play board games and read stacks of books together and then realise we're late for the cinema or theatre and rush out, leaving them lying around. And when they were small I used to make them dressing up clothes on the sewing machine very often, so there were always fabric scraps around.
So, the justification for an untidy house is that I am busy having fun with my DC. But they have a bath every night, and clean clothes every day. I can't stand seeing children in scruffy, torn or grubby clothes.
They also have fresh food cooked from scratch at every meal (porridge, scrambled eggs etc rather than just toast and cereal.) That takes time and makes mess, too.
I hope I am a good mum. I put far more effort into being one than I put into anything else in life. But my energy is finite and once we're done playing I really am too knackered to mop the floor, so it gets left for one more day, then one more...
In an ideal world, the house would be immaculate too, but I'm too knackered and other stuff, lots of it, has priority over housework.