Let me set aside the amusement of channeling Dr. Strangelove for the moment. For you, cheese has a taste or smell you dislike. For me, sweet tastes tend to be overpowering and I tend to steer away from them for the most part. Ketchup, if tangy enough, is OK on fries; however, in places where I can choose less sweet options, I do. It goes alright with American style yellow mustard, which tends to be heavy on the vinegar and light on mustard flavor, but that is largely because the extra vinegar cuts the sweetness of the ketchup. If I'm choosing the mustard, sweet isn't generally a flavor I want and even if I've chosen a sweet mustard I prefer to leave the balance of flavors intact.
Yes, this means that I tend to drink my coffee black, I pick beer over soda, I gravitate towards the darker forms of chocolate, and so on. I avoid corn, carrots and sweet potatoes for much the same reason, I find their sweetness overpowering and I prefer to dose even a regular baked potato with substantial amounts of sour cream and butter. Unlike your problem with cheese, I can tolerate some sweet things, but only when I feel up to it.
There are some forms of ketchup that are less heavy handed with the sugar, but as one starts adding things like extra spice I find myself skipping straight to hot sauce or in a pinch even some forms of BBQ sauce. Ketchup itself really is like a PUG for me, it will do in a pinch.
And I'm totally with you, mustard is way better.
