Just like a Chinese horse painting usually has 7 horses on it, a wrist watch advertisement (on TV or magazines) usually shows a 10:10 (ten past ten). Never notice it? From now on, on every watch advertisement, have a look at the time shown and you’ll find out that about 90% of the ads will give you a 10:10.
I’ve been wondering about this for long and have been asking my friends about it, but no one had a definite answer, besides guessing around.
I’ve decided to do some Googling on the web and found out that the best answer is because a 10:10 will not block the clock’s manufacturer logo/branding on the watch, which is usually located above the center of the watch.
Of course you can also show an 8:20 , but it will display a “frown face” whereas the 10:10 will give you a “smiley face” 
More discussions about it here if you are interested.
