I found that the way an establishment serves a martini, is very similar to the quality of the meal. The Beverage Server is just as important as the chef. Some establishments hire bartenders/resses for looks as persay to one who can conjure up a very good drink. It really denotes the type of service and food one can recieve just by how the drink is prepared and served.
Why three olives? A story I read about a poor woman who sold flowers on the street, no matter what the weather conditions were, this woman always had a smile on her face. .. one inclement day, a gent approached and asked her how she could be happy all the time...She replied, "I think of Jesus and how all the suffering he went through...and then on the third day he rose from the dead... So if things bother me , I wait three days and it always gets better!" And that my friends is why a martini has to have three olives... by the time I consume the last of the olives, the martini is finished and I'm feeling all better too!
Cheers!