Where to check a company's validity?

[keepsingin]

Ok, so it's nowhere to be found on SOS, BBB, local chamber of commerce, etc. This "interview" lines up exactly with this sort of thing https://www.linkedin.com/pulse/beware-sc...rles-abell
some of the wording and questions were exactly the same, although my experience did not have as obvious give-aways as the one in the article.

Now I'm very skeptical of all the other offers I've received, lol. What should I ask in the very beginning to ward off scammers but not blow away legitimate offers?

Edit: Is asking for Tax ID# or registration info right at the beginning too forthright to blow away a valid offer? Some of these companies cover their tracks so well that google searching isn't enough, they have reviews and they make sure none of their info conflicts.