Very fast, the interviewers (agency owners) don't really know too much so it's pretty easy to dazzle them with big words and point to your experience. They're really just looking for someone who says they can do the job. The interview is mostly about your vibe and if you're willing to play their game. If they sense you'll have an issue with how their agency is run, then they'll go with someone else. They really just want someone who has a good vibe, says they can do the job, and won't challenge them too much.