As clear as mud.

Understand the thought

Meaning in plain English

Something presented as clear is actually confusing or difficult to understand. The comparison is usually ironic: mud supplies the opposite of transparency, so the phrase can gently or sharply challenge an inadequate explanation.

What the words are saying

The expression combines clear with a material that obscures rather than reveals what lies beneath it. The contradiction gives the remark its ironic force. A speaker may use it after receiving instructions that leave the important point uncertain, or to acknowledge that their own explanation has become muddled. Its effect depends on tone; a joking response can also sound dismissive to someone making a sincere effort. The useful next step identifies what remains unclear and asks for a concrete clarification. The phrase names confusion but does not itself diagnose the cause or supply the missing information.

Everyday example

After a booking email gives two incompatible arrival times, a guest remarks that it is clear as mud and asks which time applies to their reservation.

When to use it

Use it to point out confusion in something described or expected to be clear.

Agent-assisted editorial interpretation. This explains the words; it does not by itself verify their author or earliest origin.