Most Helpful Girl
Dressing for success is a real thing. If you went into a job interview in sweats and a t-shirt with your hair in a sloppy bun on top of your head that interviewer would automatically assume you treat your work the same wa you treat yourself. It also makes people think you don't care and are not invested in whatever you are doing. I'm not saying to ditch all of your hoodies and yoga pants, but there is a time and a place for everything.
Most Helpful Guy
Absolutely. Your appearance makes others get additional thoughts about you.
Example: Employers look at you and try to figure out how your look will affect (or effect) things related to the job you're applying for. If you don't know how to dress for work then others might get negative views about you and even the workplace depending on what it is. So your appearance totally matters.