Sorry to be a critic.
People who say "[insert condiment here] on a hot dog" is a food sin need to think about that for a sec.
It's a hot dog.
Can it be treated as well as any other food? Of course! There's actually a place in Boston that I enjoy called The Lower Depths. They offer an entire section of the menu for hot dogs only. Basically, you pay $1 for a hot dog and then you pay extra money for toppings, and there are tiers. The basics are free (ketchup, mustard, relish, hot sauce), but above that there are more substantial toppings for $1, $2, and $3. For example, I think things like cheddar jack cheese and spicy aioli are $1 and things like guacamole are $3.
I got three hot dogs with good toppings for less than 10 bucks. Awesome.
However, in the end, while we can dress up hot dogs in any fashion we like, they're still hot dogs, pretty much the lowest form of meat on the totem pole other than, what, scrapple? I can understand why putting ketchup on a steak can be seen as a food sin (not so much steak sauce, which I think is perfectly fine), but putting ketchup on a hot dog seems perfectly apt given how hot dogs are regarded in the meat world and how ketchup is regarded in the condiment world. Neither things are particularly gourmet or extravagant in their essence but they are tasty so what's the problem with combining them?