I went to the Yocco's west side location on Hamilton recently. I had heard of this place years ago from a hot dog distributor who was delivering to a great hot dog place in Glens Falls, NY. The guy raved about Yocco's. I was in Allentown on a business trip, so I had to go. If you're looking for a fancy place, go elsewhere. If you're looking for a classic working-class hot dog, this is the place to go.
The hot dogs are well-done, and done well. The sauce has a kick to it (which is different from the sweeter Greek-style meat sauce which can be found in Glens Falls or in Troy, NY).
I had three dogs, fries, and a Coke, and I was full afterwards. The presentation is simple: the hot dogs are placed on a tray. No plate, nor is there a need for one. The soda is cold, the fries and the dogs are hot. The service is friendly and extremely efficient. I don't know how the other options on the menu are, but I was there for about 20 minutes and didn't hear a single person order anything other than hot dogs with the works.
The customers are a cross-section of society. While I was there I saw two elderly couples, five young families with young kids, and three groups of teens; there was racial and ethnic diversity as well. It was America at its best: people from all walks of life enjoying good food.
If you are in the Allentown, PA area it's worth looking for a Yocco's. It's not fancy. It's not loaded with a bunch of newfangled stuff. They just serve good-tasting hot dogs with a great chili sauce.