Are "properly designed" and "given application" escape clauses?
No, not at all. I'm just stating this caveat because you *can* improperly design a cable and make it sound different. You can make speakers cables that have too small a gauge for a given speaker's impedance, or the required cable length. You can make interconnects that have improper impedance, bad shields, poor insulators, or some weird geometry that increases inductance or capacitance beyond some reasonable trade-off of values.
For example, a speaker with a minimum impedance of less than 2 ohms that needs a twenty-five foot cable run is not going to be best served by 16 gauge cables - a 16 gauge cable in that scenario may indeed cause audible differences, and there won't be any mystery why. It'll be measurable.