If you expressed your dislike, would you improve anything? Would you educate or alienate them? We are nice to those we don't particularly like because it's the civilized way to interact. While not a personal connection or extension, it's a product of human respect and (difficult though it may be at times) it's the better choice to make, the more polished approach. You may not respect that individual but, if you express that distaste or rejection, you will accomplish nothing praiseworthy. Ever wonder how health care personnel often seem to manage great patience with obnoxious or very demanding patients?
These people are but a passing storm or bump in your road. Don't let them take the joy out of your life. If you must, make a game out of countering their unpleasantness with patience and kindness. As you move past them, they may marvel at your professionalism or polish without really knowing that you really don't like them at all!
A work environment is (or should be) a collaborative effort, a team. If you express your dislike, you will erode the fabric of that teamwork and the possibility of productive cooperation. At day's end, you can take some satisfaction in your self-discipline.