The trick to using a fishpole or boom is to remember that they should always be pointed at the subject and angling up or down--never horizontally.
Here's why: Booms and fishpoles are highly directional. If you point them horizontally at your subject, they will pick up her voice AND all the noisy stuff going on behind her.
This explains why camcorder mikes often do a lousy job: they point horizontally--and often pick up unwanted sound behind the subject.
A boom in use on a TV western. Note how the boom operator is on a ladder. That's so that he can point the mic down on the actors, to ensure no background sound is picked up.