Are there any "underground" openings or gambits? Playing a lot of blitz online, from time to time I meet quite strong players who regularly use very dubious lines that can have some shock or practical value in blitz or bullet chess, such as these, as White:

[FEN ""]

1.e4 e5 2.Bc4 Nf6 3.Bxf7+


Or, as Black:

[FEN ""]

1.e4 e5 2.Nf3 Bc5 3.Nxe5 Nc6




[FEN ""]

1.e4 e5 2.Nf3 d6 3.d4 Bg4 4.dxe5 d6




[FEN ""]

1.e4 d5 2.exd5 Qxd5 3.Nc3 Qe6+ with Qg6 and an early Nc6-b4 attack


I was wondering if all of this means that some players have their private analysis of some (objectively bad) lines for use in speed chess. 

Are you aware of other similar lines? As you can see, I don't mean Grob's Gambit or Cochrane's Gambit, but the very bad lines...
In bullet chess (1 min or less), you basically don't have time for thinking and will pre-move or make moves instantaneously often making assumptions about your opponent's moves. In such situation playing the best moves becomes less important; basically you just need to move fast without blundering too much. Playing chess at such short times becomes more about bluffing and less about thinking.

The practical value of dubious lines/moves can be two-fold:


your opponent has to think (=losing valuable time) to refute the move
your opponent plays a standard (pre-move) which is not the best in this situation


Due to the limited time it is difficult to refute such dubious lines even if you lose a minor piece. So there is little risk involved.

I doubt there is much private analysis involved.  I also doubt there is much value in trying this at longer times (3 min or more).