It is well known that club players, typically, go to pieces when confronted by a gambit. Of course, for every player there are some gambit lines which they know, and perhaps their theoretical knowledge will suffice to get them to a safe position. But this won't be the case when they are confronted by an established gambit they don't know, an unusual or forgotten gambit, or where their opponent deviates from theory.
To my mind, gambits are the situations where there is the single biggest gap between passively looking at a position at home, and facing something over the board. Skimming over an opening variation with a cup of tea, maybe Rybka muttering in the background, it all looks so straightforward - an "=" symbol (or something even more favourable), a bunch of crisp responses demonstrating the intellectual failure of our opponent's adventure.
But at the board, things are rather different. First, there is the confusion factor...
Yes, indeed. At the level of play that the Jerome Gambit is exhibited, it is often "unusual" or "forgotten" enough to lead to success. Certainly it can lead to "confusion".
"Knowing" that the opening is refuted, looked askance at by "the book" and hooted at by computers, it must be infuriating (or embarassing) for the defender to be struggling against such a monstrosity.
I am remined of the story about chess great Aaron Nimzovich climbing on a table and bemoaning "Why must I lose to this idiot?" More recently, Bill Wall shared the scolding he received from his opponent after having the audacity to play - and win with - the Jerome Gambit. The opening is garbage, it would never work against a grandmaster, the world champion would never play such a thing...
Ah, yes. In my pre-Jerome Gambit days I would repeatedly defeat a friend who always protested "But I was winning!" I would reassure him that, yes, he was winning, right up to the point where I checkmated him.
(*I am enjoying Collins' work, and I appreciate the classic games that he chooses to illustrate his points. I was surprised, however, in the mentioned chapter, that after all that he wrote of the tribulations of "club players" he chose a game between super-Grandmasters Anand and Shirov to drive the point home.)