Actors, jugglers, tumblers, travelers. Mobile festivals, road-worn thieves and highwaymen. The road is a dangerous place, and one filled with the kind of people you don't really want to interact with. Since time immemorial, traveling actors have been lumped in with the worst of the worst of all humanity. Theater troupes were considered unclean as far back as Ancient Rome. In the Middle Ages, actors were classed with prostitutes. This class of wanderer is perfect for an adventuring party considering how outside of the rest of society they were. They lived beyond its borders, away from the normal ebb and flow of social norms. None were so hated, yet permitted such liberties as to stay in castles and manors to entertain.
There is a certain truth to this that we have forgotten. When one hears about how much actors were reviled, it seems a quaint antiquitism. However, the theater troupes and traveling fairs of the ancient and medieval world weren't so much like fine playhouses. The Globe isn't what we're talking about here. They were more like modern-day carnivals that come and set up in a parking lot. The people that were mistreated weren't so much like grand Shakespearan actors of stage and screen, but rather more like carnies running old rickety rides.
Traveling theater and traveling fairs serve a minor social role in Arunia, mostly fueled by the gnomish and halfling urge to wander. Gnome wagons on the road in long caravan foretell the coming of a festival to town: archery contests, and minor enchanters. Singers, and jugglers, and other such entertainments are sure to follow. But like any good American carnival, there's also hangers-on, thieves, and sideshow entertainment. I've never seen concrete evidence pushing the tradition of the carnival back to the middle ages, but nor have I seen any good refutations.
Just being someone who travels the roads opens you to suspicion. Decent, gods-fearing folk don't go tramping from place to place. The lowest grade of people travel constantly. These are temporary workers during the harvest seasons (of which we do know many many existed), the rootless survivors of wars, mercenaries, highwaymen, bandits, and drifters. This class of folk is where adventurers fall in the Arunian mind and in the minds of many in settings like Greyhawk.
Of course, there is something redeeming about these kinds of people as well. Adventurers aren't just highwaymen—they're Bonnie and Clyde. They aren't just festival folk—they're P.T. Barnum. There is an undeniable attraction to the illicit and forbidden, and adventurers skirt the line where the forbidden touches the mundane, as do carnivals and festivals. It's quite natural, then, that they should travel in each other's company or otherwise intermingle. Of course, this isn't always how it works out: frequently, adventurers may in fact shun festival folk on the grounds that they are therefore elevated by having someone below even them.