as clear as mud 不清晰；混乱；一点也不清楚

【例句】
The fate of the fiscal pact agreed in Brussels on December 9th remains as clear as mud.
12月9日在布鲁塞尔达成的财政公约依旧是不清不楚。

Your report was badly written, it was as clear as mud.
你的报告写得很糟，简直看不懂。