there is an article years ago, mentioning that Hu was rebuked in front of others by a general in one meeting or event, I forgot which one, but it happened near the end of his term. As for corruption, I doubt you can find anyone clean 100%, including Xi. Corruption come in many form anyways, some even in legal form, yes, you can legalize corruption too if you want. But the problem with Jiang, is that he allowed it to run rampant, and by weakening his successor, he made it impossible for his successor to control it. That's why Xi has to take drastic measure to curb the corruption.