They presented an appearance of being 'clean' (self-restrained, not involved in carnal matters), but they were dirty inside: they seethed with hidden worldly desires, carnality. They were full of greed and self-indulgence.

1. They presented an appearance of being 'clean' (self-restrained,
not involved in carnal matters), but they were dirty inside: they
seethed with hidden worldly desires, carnality. They were full of
/greed and self-indulgence/.
2. They exhibited themselves as righteous on account of being
scrupulous keepers of the law but were, in fact, not righteous:
their mask of righteousness hid a secret inner world of ungodly
thoughts and feelings. They were full of wickedness. They were
/like whitewashed tombs, beautiful on the outside, but full of
dead men's bones/.
3. They professed a high regard for the dead prophets of old and
claimed that they would never have persecuted and murdered
prophets when, in fact, they were cut from the same cloth as the
persecutors and murderers: they too had murderous blood in their
veins.