So when your 4C is upright, it's carb is upside down, thus wouldn't work "too well" by your logic, right? Wrong both ways. The only thing affected with any of them is the starting. And once you've got the plumbing right and figured out what they need for choking (some don't need it and work just excellently well, some do and don't work very well) they usually aren't much problem.

There have only been a few engines that are difficult to handle when their carbs point down. Most often, it's when they need manual choking to prime, and since 2 cycles usually have the carb in front, where you can reach the carb easily even if cowled. Only 4 cycles that need manual choking have a problem when their carbs point toward the earth and are inside cowls.