It's abuse if the mother is mad and she's doing it to inflict vengeance or revenge.
It's discipline if it's established ahead of time that it's the punishment for misdeeds, and if she handles discipline without showing anger...
IMO, It's no worse that putting soap in a mouth for swearing...
That's the key. I spanked (like very lightly, didn't even hurt my kid) once b/c I was getting so fed up with his crap. But I did it b/c I lost my cool for a second. Man, did I feel bad for doing that. I still do and it was like 4 months ago. However, if I tell the kid "if you get out of bed again, you're getting a spanking", then he gets out I follow through and don't feel bad.
I would not "hot sauce" my kid though. Some people are very sensative to hot sauce and it could really hurt without you knowing how bad you are hurting them. Plus they might associate spicy foods with discipline and I wouldn't want that for my kids. Also, I think it would be double pain b/c the hot sauce would burn their o-ring on the way out.