I am looking an expression that could mean "eager for someone to make a mistake so as to criticize them?". This is to be used in the instance where a famous personality has a lot of critics, probably jealous of him. They read too much into what he writes and tries to criticize him. They are eager for his new writing with the sole purpose of criticizing his writing and him.
Example:
You should be very careful when you go on twitter. There are people _________________________________ (who expect you to make a mistake so as to criticize you).
I was wondering if there is something like "thirsty for you blood", not sure.
Best Answer
ready to pounce
In the OP's example:
The image is of a cat ready to pounce on a bird or a mouse -- or a lion or tiger ready to pounce on a deer. See Images for ready to pounce.
pounce. Oxford Living Dictionaries. See especially the third definition below.