If I have hubbys car, it is usually easy to find as it is quite a tall car and has roof bars on it - he took the bars off it last winter and I hadn't noticed and it took me a wee while to find it but luckily it wasn't a big carpark. I have a black clio so my problem is that there are so many that I often try one or two before finding mine.
When our daughter was six and I collected her from school I had to wait for her to approach me. If that didn't happen, I was in grave danger of taklng someone else's daughter. I never did notice anything about her that distinguished her from lots of her classmates. Well, same uniform, blondish, average height....Always wondered how her mother managed !
And my father, many years ago, once drove off in someone else's car. He was at a race meeting, finished early, the key fitted the car he saw as his and he drove it twenty miles before he looked in the glove-box to get some sweets he kept, didn't find any and then realised. He drove back to the course and left it in exchange for his. His mistake could have been easy to make, the key working, but for one thing.. His car was a different colour.
My form tutor, whose been my science teacher for 3 years had always had a moustache. At the start of this september he'd shaved it off, but i only noticed last week!