I came across 江信江疑 in this tweet about a meme. It clearly has something to do with Jiang Zemin / 江泽民. It seems to be quite commonly used; my guess is that it's something people say on Internet that refers to politicians, or heads of government, and their trustworthiness (or lack of it). But this is just a guess.
What does 江信江疑 actually mean? What's its "back-story"? Is it just used online, or could it be used in spoken Putonghua? Perhaps a few sample sentences would be useful too.