I think I'm judging a salesman for giving off a "creepy vibe."
What makes you think he's being creepy?
His looks and the way he walks and talks or maybe something else
Just because someone is different than you doesn't mean they're creepy.  People should be free to act however they want as long as they don't harm others, even if the way they act is strange to you.  It's not okay for you to judge them over it.
I can't help judging him. He's just so creepy.
I know it's difficult, but you should really do your best to not judge him for being a little odd. He might be a perfectly nice person, if you got to know him.