What do you do when an applicant just shows up at the office? I had one rather decisive employer who would immediately disqualify any candidate who showed up uninvited. This was back when the job-hunting wisdom looked more favorably upon the dropping-in-to-check-up routine, too (which I never understood in the least, btw).
I figure that showing up uninvited anywhere is such terrible manners that it says something very unflattering about the person who does it. I sure as hell wouldn’t hire someone with such an underdeveloped sense of etiquette. I barely tolerate it with family.