Another question about THE MAN FROM BARBAROSSA

English is not my native language. Could you help me with another passage from TMFB?

Michael Brooks tells Bond and other agents about three hapless guards of SoJ he’s taken out and hidden their bodies.

“Should be a hue and cry, but they possibly get the odd idiot going over the wall here. Either that or their organization’s porous”

Bond did not recall the old expression, “porous”, for a moment, then smiled as it came back to him. Porous stood for “Porous piss”.

Could someone translate it to plain English?
Who’s the odd idiot? The third one? And what this porous piss has got to do with the SoJ and the guards? This piece sounds a bit confusing. Thanks

“Odd idiot” = every now and then, some random person or other.

“Porous piss” = phonetically, “poor as piss”, AKA “piss poor” or of very low-quality.