Marianna Spring, from the BBC's Selfie Dissemination Unit, certainly likes her exclamation marks!
It's a toss-up as to which appear more in her tweets, photos of herself or exclamation marks!
Not that I'm innocent on that front. I learned from Sue that too many exclamation marks are a bit much (like laughing at your own jokes, as F. Scott Fitzgerald once remarked). I have been trying to limit my use of them ever since, not always successfully!
The best time to use them, of course, is when you're marking an exclamation - eg, "Lawkabiddy! That's a biased report!" - though they are certainly useful for suggesting that you're feeling perky today as well.
LAWKABIDDY, if you're wondering, was an 18th century exclamation of surprise or astonishment. I recommend it to Marianna. She should start all her tweets with it.