DS is 3. He's mostly reasonably well behaved, but if he's tired and/or hungry he'll act up. I try to respond to this calmly, explain what is wrong with his behaviour, and tell him what I need him to do (e.g. "DS, I know you're tired, but you can't lie down on the pavement. You need to take my hand and keep walking; we're nearly at the car"). This usually works fairly well.
However, DH gets much more wound up about DS's behaviour than I do. He'll start yelling, which generally winds DS up and the situation gets worse. What I'm most concerned about, though, is that DH gets really sarcastic when he's angry.
So, today, when we were out shopping, and DS got tired and tried to sit down on the floor of a shop, DH started yelling "That's great, DS; I'm SO glad you decided to sit down! This is turning into such a great trip!". Or if DS spills something, DH will say "Oh, well done, DS, that's great!" and stomp off to get a cloth (my response would be more like "Oh, DS, you spilled that and made a mess! You need to watch where you're walking! Now go and get a cloth to clean it up". And then once we've cleaned the mess up, I'll show him that he should leave his cup on the table in future, not on the floor).
When DH starts yelling, DS just stands there looking confused. He clearly has no idea what to do. I'm aware that it's not an effective way to discipline him, but I'm worried that it might actually be damaging. Does anyone have any thoughts on whether sarcasm in that kind of situation could really hurt DS? Should I talk to DH about it and ask him to stop?