Attended an interview, interviewer started calling me sir (Which I took as sarcasm).

Giving so many interviews, I was use to basic oops question. This guy just offers me a job based on my resume.

Felt nice but fishy.

Hmmm I'm always hesitant if someone will hire me right away like that

Honestly I think that's a good way to do it. All the research I have read says that interviews and even coding tests really don't tell you jack shit. If their resume looks good and their references show that they didn't make it all up might as well go for it. You are just as likely to get a dud or a genius as you would be if you spent hundreds or thousands of dollars extra on vetting them.

@catadoxa good point - I never thought of it that way.

I always feel I need to scratch the surface a bit if a job offer comes too quickly.