When is tbagging acceptable?

What's yalls threshold for tbagging? I personally only tbag if either someone loses a jumping, or if they have been meat riding/chased me around for minutes. Very occasionally I will also tbag someone who koed me if I res and kill them but that depends if they tbagged me or if they were obnoxious about killing me.

Also what's yalls go to tbagging strat? Mine is spam running on them because cementoss's running animation is goofy, same with his melee slap animation. But I've seen spam crouches, spinning in circles, or the classic emote spam.