People make judgements about other people all the time.
They judge by your clothing, hygiene, posture; by the certifications and degrees hanging on your office wall (or lack thereof). They judge books by their covers and backside overviews, and they judge websites and companies by how many likes they’ve got on Facebook. They judge authors by how many titles he’s put out, and how popular those books have been. We Judge. This is just a part of the way the world works.
Generally speaking, stereotypes and generalizations don’t spring up out of a vacuum.
There are always exceptions, and having learned that a long, long time ago, I don’t even have to consciously try to be receptive to a change in my perception of a person. It comes naturally to me. But… There’s a reason books have certain covers, and there’s a reason people dress a certain way. These things, whether you intend it or not, affect the judgements people make about you.
Pretending otherwise is a waste of time, and expecting other people to look past the surface is unreasonable. The surface is the first thing people see, it’s what most folks rely on to decide whether they want to delve deeper. Seems pretty sensible to keep that in mind if you ask me.
Right or wrong, people judge.
Might as well use it to your advantage, even if only to brace yourself.