I think SPs come by "charm" most easily.
It's an easy-going, easy-to-get-along-with quality.
It's the ability to get other people to do what he wants by his goofiness, winning smile,
and je ne sais quois with the batting eyelashes.
It's the quality of not taking yourself too seriously, having effervescent eyes,
and an adventuresome outlook on life - all rolled into one person.
The current American Idol contestant, Jason Castro, has this "charm",
although it's debatable whether he's an INFP or an ISFP. Based on his "charm" I'd say SP.
(But that's circular reasoning, isn't it? Oh well.)
watch this interview