Water usage is probably my biggest. Living in a high desert, my wife and MIL see no problem with filling one side of the sink with hot soapy water to wash a few dishes because “that’s just how I’ve always done it”, to watering the grass and plants for hours. All of this makes me mental.
If someone is trying to sell me on a cafe or restaurant by saying, ‘Yeah, it’s kind of expensive, but there are great deals on the app…’ it’s no dice from me.