Stupid question

Hook up an electric bass cab backwards and see exactly what I mean. I worked with a bass player who did exactly that and the cab sounded pretty crappy until we re-wired it back to the proper polarity..."el sucko wrongo a mundo"...lower output, weird sound, and all of his fellow musicians pointing at him and laughing (not really as he was/is a very good bass player).

What Achilles said, and to add to that: The thing you don't want to do is hook one speaker one way and the other speaker the other way. Then when one is pushing the other is pulling, hence "Out of phase."
Hooking both "black to black / red to red", is 100% the same as hooking both "black to red / black to red"

Inverted phase?
Sucking out?

I believe you guys are making that stuff up.

If it starts smoking you have it backwards, or there may be some other problem.

Try it. Any one speaker guitar or bass amp...hook it up backwards and it sounds bad. Period.

I believe you, Wolf_garcia. I've heard it myself in my friend's miswired mid-fi stereo. (He heard it too.) I'm just at a loss to explain why it matters.
BTW, I'll see if I can run your experiment on my bass amp this weekend.