Exactely when do you put 'even' before the comparative words?
One of common mistake that non-natives say is something as below. (B is a non-native here)
A: How was the movie? (expecting a good response)
B: It was better than I expected. (meaning it was even better than he thought)
A: Oh... well... (disappointed and thinks B didn't expect the movie that much)
As such, some of Youtube English classes mentioned that if you say like B did, where something is just better, not even better, than the other thing, then automatically the other thing feels not much at all.
So, I thought until now that if something is great already, and if you like to emphasize the other thing is greater than that, you should always use 'even' before the comparative word. Like "The cake tastes great, and the liquor is even greater", not "liquor is greater".
But I saw today, in my grammar book, this sentence below.
I am pretty tall, but my dad is taller.
And here I'm confused. Why didn't they say "my dad is even taller"? Is it because of the word 'but' here? What's the golden rule of putting 'even' before the comparative words at all?