I'd still blame the individual developer for poor naming. Naming a variable something like int_list is terrible in that it's both very specific and semantically meaningless. Either choose a semantic name like grades or part_numbers, or take a hint from ML convention and use semantically void names like "xs".

Sure, but is there anything stopping the person updating from revising the name? The original quality of the name is not relevant to my point, which is that anyone changing the code but leaving poor names behind is complicit in the debt.