Green’s Dictionary of Slang

moody adj.

illicit, untrustworthy, false.

1958		F. Norman Bang To Rights 74: So one day they had a moody ruck and made out that they had a punch up.
1962		R. Cook Crust on its Uppers 20: Moody rabbits in Spanish bars with my heart going like an outboard motor.
1975		‘P.B. Yuill’ Hazell and the Three-card Trick (1977) 57: They were the moody audience, the ones who let the whole street know this was where to cop easy money.
1989		J. Morton Lowspeak 100: Moody – dishonest, stolen, lies.
1990		in D. Campbell That Was Business, This Is Personal 19: I went into the bank in a suit and was writing a moody cheque out.
2007		N. ‘Razor’ Smith Raiders 80: They [i.e a pawnbroker] wouldn’t have it [i.e. a watch] .They said it was moody and threatened to call the law.
2011		J.J. Connolly Viva La Madness 40: Some moody swell, some posh cunt, on yer splendid holidays.
2022		Twitter 25 Nov. 🌐 Shysters pedalling moody goods for variable prices.

In phrases

go (all) moody (on) (v.)

(UK Und.) to fail, to go wrong.

1977

D. Powis Signs of Crime 193: ‘It went moody on us’ would mean that the expected successful result did not materialise.