Pfffft, you've gotta be kidding me.
As an ISTp, I can assure you that no one
ever approaches me. People have labeled me as intimidating, snobbish, aloof, etc.
However, on the other hand, I can identify with your first sentence. Those that manage to break through the sour candy coating to the delicious nut inside characterize me as laid-back, cool, and fun. I've even been teased jokingly/lovingly about my shyness, which just makes me blush, which makes the teaser's eyes and face just light up, which makes me blush a little more, which makes them light up even more, and it just turns into a big giggly vicious circle.
Honestly though, I think more than anything I just end up feeling left out, misunderstood, forgotten, and lonely. That comment that someone else made about ISTp's being walking contradictions really resonated with me.