You look at a herd of cattle and well, they all look the same... but they know. They all have an individual personality, and those personalities change from day to day. They can have their grumpy days and their happy days and their serene days. But it's unpredictable. You can't be off in outer space when you're dealing with animals.
There's a fine line between angry and grumpy. Angry isn't nice, but grumpy is funny.
I've had a fair amount of experience with snakes, and I find them to be pretty honest in terms of how you read their body language and emotions. They'll tell you when they're grumpy. They'll tell you when they're okay.
In actual life I am a grumpy old bag.
I can be a bit grumpy. I'm full of angst, and hormones.