Telling people the proper method for dressing their hot dog is like telling them what outfit pairs best with crocs. Hot dogs are literally the worst meat substance that's deemed safe for people to consume; you can't be snobby about what people choose to put on it. It's not like they're dumping A1 on a rib eye.
For what it's worth, I prefer my hot dogs with ketchup, mustard, relish and onions, and maybe some shredded cheddar. As I don't usually have all those available (and if I'm eating a hot dog, I'm probably feeling pretty lazy anyway), ketchup and mustard work in a pinch. And cheap, yellow mustard; I save the spicy brown mustard for an actual decent sausage.