Many officials who engaged in corruption and bribery once had their own ideals and ambitions, but they couldn't resist temptation and ultimately chose to fall.
This may not be entirely accurate. Besides temptation, the bribe-givers have too many methods, and inducement is just one of them; sometimes coercion or even threats are options too.
From Tang Mo's standpoint, such bribers are virtually destroying the officials he carefully cultivated, nearly undermining the Empire's foundation.
Thus, he seriously considered whether to severely punish the bribe-givers as well, allowing those bastards willing to corrupt the Empire's officials with money to experience his methods.
Frankly speaking, in an Empire, as long as the Emperor consents, some shady departments have the full capacity to let a person experience what it means to live a fate worse than death.
