What IS he? Just a man? A monster/man? Is he possessed by Bob? Is he mad? Does he know stuff we don't? What does the "candy coloured sandman" mean to him? Is HE the candy coloured sandman? Is he maddened by not being the sandman anymore? 

Speculate.

 A few years ago, I read an interview with Dennis Hopper in a magazine, and they asked him about his role. And his response was that to him (how HE treated it), even though he didn't come off this way, he acted as though it were a love story, and he was so madly in love, so desperate to be with her, that he would do ANYTHING and not let anything get in his way. His desperation made him mad and delusional.

 And thats quite genius, IMO. Because I know how paralyzing desperation can be where you are helpless and just want to make buildings collapse by exuding your anger, disappointment and frustration.

In a very Lynchian way, I suppose Blue Velvet is a love story.

Lynch actually said it too. He said Booth was in love, he just "was not very subtle about it".

He also said Booth was a comical character. I think he's just a sociopath, with both his scary and pathetic/comical sides.

BOB, on the other hand, is an abstraction and a character who's in control of what he's doing, unlike Booth.

So why does he react to music like he does? Like it means more to him than we would know about from the film. I get like this. I have unusual emotions that seem to be just beyond my understanding. Music often triggers them. I think Lynch may know what I'm talking about. He probably gets them too.

I reckon Booth is the son of the woman. I don't think there ever was a dad. It's an emaculate conception. Booth is Jesus. The Candyman is God, and Jesus himself.  

Or... 

Why are you complicating things like that ?

There is nothing supernatural in Blue Velvet. It's a straight "young man on the side of Good curious about  dark stuff" story.

Booth is simply a sociopath, like Lynch likes to create. Like Peru in Wild at Heart, M. Eddy, etc.

There is not a soul in the world that doesn't respond to music.

Remember the scientific, ultra-efficiaent Laputans in Gulliver's Travels? Language and poetry were looked down on as frivolous. But they loved music, and created the most beautiful in the world.

Lynch frequently comments that words can't explain what he can convey with his images.

Music is raw expression. "In Dreams" expresses a longing that Booth can't.

Did you know that Lynch tried to get "Crying" for that scene and couldn't?

Both are about losing love, and an agony of lonliness. Booth is angry and violent because of his sad lonliness and feelings of isolation from real love.

There is not a soul in the world that doesn't respond to music.

Remember the scientific, ultra-efficiaent Laputans in Gulliver's Travels? Language and poetry were looked down on as frivolous. But they loved music, and created the most beautiful in the world.

Lynch frequently comments that words can't explain what he can convey with his images.

Music is raw expression more effective and less easy to misunderstand than words. "In Dreams" expresses a longing that Booth can't.

Did you know that Lynch tried to get "Crying" for that scene and couldn't?

Both songs express losing love, and an agony of loneliness. Booth is angry and violent because of his sad loneliness and feelings of isolation from real love.

Ben:  "We've laid in a gala reception for your fair-haired boys tonight.  All of Twin Peaks' best and brightest."

Jerry: "We're holding it in a phone booth?"

 Thats funny. I was introduced to BV in a film class in college called Bad Guys In Film. We watched about 30 seminal movies dealing with the different types of villians....even geniously suggesting Office Space was a bad guy film and Lumbergh was the stately father figure.

Anyway, each film was grouped under different categories, and Frank was under Monsters. But not like undead monsters...the other connotation. So when I read the description of "beneath the surface of a beautiful suburban town"...and i see the bugs crawling, I was expecting an actual monster.

Nothing supernatural? What about the Robins? What about...stuff.  YEAH, The stuff.

Lynch doesn't know diddly about what he makes. He admits that. So I'm telling you what they are about. Booth is the antichrist, demoted to local thugster. Because as we all know the apocalypse is constantly being postponed. Jeez, EVERYONE knows THAT.

He is the mirror kickback of Christ, and Christ himself. The Robin is a symbol of Christ. The Robin is the animal part of Frank and the candycoloured sandman. Seperated from the child Booth. The torments of Frank are him recalling being Christ and unable to become the antichrist and get the hell out of this dimension at last!

He is father and son. Dorothy's (The Door) is the pain of birth.

Don't make me come back there!

Velvet is from Reindeer antlers. Another reference to Christmas and Christ. Blue was Mary's colour. Blue Velvet is a blue reindeer.

There's no point asking a question if you get mad when somebody gives you an answer.

There is no basis for anything you interpret in your last post. Blue Velvet is a simple, straightforward film.

Also, David Lynch has no problem explaining plenty of his movies. He said Lost Highway was a psychogenic fugue, the Mystery Man and BOB were abstractions...

He always described Frank as a human being with mental issues and there is absolutely no basis to pull antechrist stuff. He's partly a comedy character.

Oh boy, I would have loved to see Frank saying to Dorothy what her mother sucks in hell...

I dunno for sure, beyond that he is a very troubled man....

But I sure know there has got to be an S+M club just crying out for a Frank Booth 'Booth', ideally the club would be called 'Now it's Dark'.