Describe the affirmative defense of entrapment and explain why it is not always easy to prove

What will be an ideal response?

Entrapment occurs when the idea for the crime was not the defendant's but was, instead, put into the defendant's mind by a police officer or other government official. Entrapment is not always easy to prove. Police are allowed to set up legitimate "sting" operations to catch persons engaged in criminal activity. The key to a legitimate sting is that the defendant was "predisposed" to commit the crime; the officer did not put the idea in the defendant's head. If an officer dresses up like a prostitute and parades around in an area where prostitution is rampant, a potential customer who solicits sex could not raise the charge of entrapment against a charge of soliciting a prostitute. It is often difficult to predict whether the entrapment defense will be successful.