IANAL, but I've heard that entrapment defenses are way harder to use, and much rarer, in reality than on TV.
First, you frequently require a judge's permission to even argue it.
But the real burden is showing that your client would not have committed the crime without the effect of the police. A cop posing as a drug dealer and offering you drugs as you pass them in the park every day doesn't count; a cop hounding you for months to commit wire fraud because they mistakenly believe you're in a criminal org might, though.
