At what sort of reading do they fail at?
Don't forget, the earth continuity pass limit is (0.1 + R) Ω, where R is the resistance of the protective conductor of the supply cord/lead.
So if for example, they were coming in at, say, 0.12Ω, this may still be a pass, as the mains lead might be contributing the 0.02Ω (You would easily know this, as you'll have already performed the seperate test on the detachable mains lead, right?).
However, if you were getting readings of, say, 0.5Ω or even greater, then it's doubtful that the mains lead is contributing that much (again, easily confirmed), so it probably is a fail.
All described in the IEE Code of Practice, section 15.4, pages 73 & 74
C&G 2377 -01 & -02