I think you mean "come *across* as (somebody/someone) ..." A couple of examples of "come across as..." off the top of my head: She speaks so passionately about global warming that she comes across as someone who is genuinely concerned about the environment. He constantly interrupts people during a meeting that he comes across as a smug, know-it-all.

If you act deceptively you will come across as dishonest. If you are going on a date you want to come across as good as possible. If you dress nice you will come across as professional. If you dress sloppy you will come across as unprofessional.