When people come in to fill out an application and bring a friend is a pretty clear indicator that the application will go straight to the round file. Also, dressing inappropriately for the job they are applying for, poor grooming, excessive tattoos (although they have become pretty mainstream, if everything else was equal the person without the tattoos would have a better chance of getting hired.)
To much perfume, to much make up, poorly fitting clothes, being unprepared for an interview, chewing gum in an interview, not making eye contact, lack of confidence, over confidence, lack of experience, being over qualified, ...