30 year teacher here. I have grumpy days and even had a grumpy year two years ago…the class was the toughest and most disrespectful I’d ever had. Every year, every day is different. You never know what you’re going to get. So if someone didn’t want to show appreciation because I was “grumpy” , they should come and observe for a day, or period. They might understand and change their attitude about teacher “grumpiness”.