* AlternateCharacterInterpretation: The story could easily be seen as Bob the {{Jerkass}} tormenting the stressed-out Dr. Marvin while everyone is too stupid to realize Bob is actually not as wonderful as they say he is. On the other hand, Dr. Marvin has legitimately pissed off a lot of people and screwed up his own family well before Bob ever showed up, and Bob is clearly a pretty nice and well-meaning guy underneath his mental issues.
* FridgeBrilliance: You may wonder why Leo doesn't just call the cops on Bob or file a lawsuit against him - until you realize that Leo is so concerned about not looking like the bad guy to his family, who already have significant problems with him and are conversely enjoying Bob's company, that he's effectively prevented from doing anything like that.
* InformedWrongness: Dr. Leo Marvin may not be the nicest man, but it is his house, his family and his vacation, and Bob, intentionally or not, is invading his privacy. He's not exactly wrong to be annoyed about Bob forcing his way into his private life.
* JerkassWoobie: Dr. Marvin may be an obnoxious {{Jerkass}}, but one can't help but feel sorry for him considering everything he suffers at Bob's hands over the course of the story.
* MagnificentBastard: Whether or not the AlternateCharacterInterpretation applies, you have to admit that the way Bob figured out the location of Leo's vacation home is pretty damn clever. [[spoiler:Bob fakes his own death and goes to the phone company posing as a detective investigating the matter, where he convinces the operator to tell him Leo's address by claiming that he would need it for postage.]] Heck, if AlternateCharacterInterpretation ''does'' apply, he's even more of a MagnificentBastard since, according to said interpretation, he played the entire cast of the film like a fiddle.
* MoralEventHorizon: Leo crosses it when he [[spoiler:tries to kill Bob by blowing him up.]] It's PlayedForLaughs, but he was being serious.
* RuleOfFunny: The film's outlandish premise and UnfortunateImplications can be looked past depending on whether or not you found the film funny.
* ThrowItIn: The scene with Bob entertaining the nursing staff at the mental institution was unscripted -- Bill Murray was just having fun.
* UnfortunateImplications: While Leo certainly is a {{Jerkass}}, Bob's actions, innocently intended or not, would generally be considered, at minimum, a gross violation of the patient-professional relationship, and probably criminal harassment, invasion of privacy, and/or stalking. This makes the rather sympathetic portrayal...problematic.
* TheWoobie: Bob. Honestly, he doesn't necessarily mean to drive other people crazy because of his craziness. And you have to wonder what happened to the poor guy to make him so unbalanced and phobic in the first place.
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