I have just been in Carrefour in a huge queue full of stressy people and experienced a truly special child (and he isn't even mine). About 7, he was SO excited because his mum had let him have a, frankly small and a bit crappy toy. He was so excited he obviously decided he couldn't wait and managed to charm his way to the front of the queue without being precocious or irritating. Cross grown up faces one by one smiled as he explained how he just wanted to get to the car because he has been waiting to get this toy for ages and has had to be extra good all holidays. There are lots of very spoiled expat kids here in Dubai, including the kid I told off for whacking the housemaid over the head in the same shopping trip. I want to extract this little boys personality and bottle it, he made about 30 hot grumpy people smile midday during Ramadan.
How sweet. I once saw two young girls open their christmas presents. Mum had wrapped tiny inexpensive toys. They opened a, frankly quite uninteresting, eraser and exclaimed, ohhhed and ahhed and went and gave mum a kiss before moving on to their next gift. Still touches my heart and that was 20 years ago!
A few months ago my 10yo ds1 unintentionally charmed his way into the cockpit of a plane, purely through managing to behave in a well-mannered and polite way despite being utterly thrilled by the flight.
You're right - good manners combined with wide-eyed delight melts cross adult hearts.