Generally, hot dog franchises do not work. There are extremely few "chain stores." This is because hot dogs are usually regional. For example, Chicago Dogs may not fly outside the midwest because of the unique toppings and brand of dog. Another region may not have those items available for distribution. In addition, an area like Jersey prefers (or may be more accostomed to)a pork and beef dog made locally vs. a Vienna Beef dog.
There are "local" franchises, such as in Connecticut(Frankies). But as mentioned above, you should only go franchise if it has the marketing power behind it, as well as the history of longer term success. That’s why Subway franchises still make money, but Quiznos are suffering (and Dunkin succeeds, while Krispy Kreme only works in the South).
Take a small business class, study about operations, costs/margins, etc. Most importantly – the three L’s: Location, Location, Location!