Last time we moved I was 8 months pregnant. It was three months after they had agreed to aim for completion because they were buying an old house which needed work and negotiations took time. They never bothered telling us this until they didn't exchange when they said they would.
About three hours after they were meant to move out, I had a small child in the car and some bored removal men. I took small child in to use the loo and they were still packing.
The garden was full of dog shit, which they half cleaned up when we were there - and flushed it down the loo (which you aren't meant to do)
The house had loads of random stuff left - photos albums, etc left in random parts of the house which we had to call them back for.
The carpets had holes in them which had appeared between last seeing it and completion. (couldn't have been covered up when we saw it - just neglect since).
They took the lights off the wall and left us with some bargain basement homebase ones, left in the boxes on the floor (reader: they didn't fit)
The house was disgusting. Filthy. It was sparkling when we went to see it, but I've never seen such a filthy house before.
They left a load of random crap round the sides of the house
In the loft they left lots of crap - a guitar, an air gun, years and years worth of magazines, you name it.
Post was coming to us for months after - even now, we get some post for their children!
On the other side, we left our house sparkling - I even scrubbed the oven for them, and a professional cleaner helped too, and we left a bottle of fizz. I cried when we got to our new house and it was so awful.