In the absence of any frantic ear tugging or eyelid twitching from either player, John and Tom need to think mathematically about this game in order to work out sensible strategies when they play repeatedly.
If Tom always bluffs with Q♠, John may notice that he is facing lots of bets, and decide to call whenever he has K♠. However, Tom may then realise that John is calling his bluffs every time and stop bluffing, so that John will give Tom an extra £1 whenever Tom has A♠, but Tom will save his money when he has Q♠. A rational response is for John to stop calling with K♠, but then Tom can start bluffing again, and round and round the cycle goes.