Vegetarian hot dogs from the street vendors in Toronto are the best. Also, in Seattle in front of the Showbox, there is a cart with hot dogs that come with cream cheese on the bun. Amazing.
In LA you get bacon wrapped dogs from the late night carts in front of all the dance clubs.
In Vienna they have great cart dogs that are spiked onto a chrome dildo and then filled with cheese. Then they take a solid bun and spike it and slide the cheese dog inside. The bread closes up over the hole. Most German cities have a version of these carts too.
NYC has Gray's Papaya, the gold standard of nasty dogs. Sorry, Nathan's....Gray's are snappier.
Texas offers beef hot links at most BBQ stands...killer.

Your idea of a hot dog place with 50+ toppings has been tried several times in many places. There is one version in LA called The Stand.

Vegetarian chorizo and Morninbg Star dogs are pretty damn good for those of you who don't like snouts and tails.