Smelly code, not a function or a module, but an overall design. You know what? do not start by WTFing the $!f*# developers who wrote it.
There are good enough cases where developers can't be found guilty, and the "criminal" in such cases are: stakeholders.
Genius developers might only reduce the ugliness level from horrible to bad, but can't make it look good by any means.
There are situations where the dev teams from tech-leads, engineering managers down to the juniors do their best and put most of pressure on stakeholders, PMs, POs & co.. trying to get an authentic answer of the most valuable question for any code designer: "towards which direction(s) the project might evolve, mid term and long term?".
Good developers might fight hard to refine the stakeholders mind and get an acceptable answer of the question.. Very good developers might add on top of that some guessing or stakeholder's intentions "reverse-engineer" armed with "soft psychological skills" and couple previous experiences..
However, what can we do if the project was initially announced to be an "internal single user CLI-only file compression tool" that magically turned into a "large-scale secure OAuth based data flow compression service" ?