With these examples, you could replace the ones that have 'like' with 'as' and it will still be a simile, and vice versa. Silent like a fox. Sneaky like a fox. Sly like a fox. As red as a fox. As thin as a fox. As keen as a fox.
It is a similie as you are comparing (something) to how sly the fox is. A similie uses the words "like or "as".
simile
The phrase "sly as a fox" is a simile because it directly compares Max to a fox using "as." If it were a metaphor, it would say, "Max is a fox."
Like a happy fox
He had fooled them all as he was as cunning as a fox. They knew he was as cunning as a fox, so they would need a very good plan to win.
simile for stuck
It is not a simile!
Since there is no "like" or "as" in the sentence, it is a metaphor.
It is a similie as you are comparing (something) to how sly the fox is. A similie uses the words "like or "as".
Smart as a Fox or Monkey ???
That is a good simile, yes.
Fled from the King like a rabbit escaping a fox.