Aidin Vaziri | Sam Smith is the kind of pop star everyone can get behind. He’s young, handsome and exceedingly humble. He also has a spectacular voice — one that during his sold-out show on Sunday night at Oakland’s Fox Theater inspired spontaneous slow dances, make-out sessions and tears. “The last time I was in this area I played a show to 150 people,” the 22-year-old singer-songwriter from London said shortly after taking the stage at the 2,800-capacity venue, recalling a stop at San Francisco’s considerably more intimate Rickshaw Stop in April. “So this is completely mind-blowing.” His humility can be deceiving.