Last one I saw was about two months ago near the sespe wilderness. You can't really mistake them for anything else if they are flying. They are huge and they have the distinct white markings on the front half of their wings.
I still don't fully follow the logic of the lead bullet poisoning claims. I've read that a single bullet is enough to poison them enough to harm them to cause eventual death. OK so one of these big birds eats a lead bullet... why doesn't the bulk of it just pass though their system having minimal effects? Do they keep it in a gullet and it just gets ground up over time?