[lixtra]

I miss: A good trap is safe - if the defender responds optimal, the trap setter is not in a worse position than before.

[tromp]

The Stafford Gambit doesn't fare well there. It requires Black to play 3. ... Nc6 in the Russian defense after 1. e4 e5 2. Nf3 Nf6 3. Nxe5 which according to Stockfish loses more than a pawn's worth (eval +2 for white after Nxc6 d3 Bc5 h3).

The Noah's Ark Trap is much safer, as black only loses a fraction of a pawn going into the line (https://en.wikipedia.org/wiki/Ruy_Lopez,_Noah%27s_Ark_Trap ).

[dmurray]

In chess theory a "trap" normally means the opposite, a move that is not optimal but gives the opponent a chance to go wrong.