Am I as dull as...

[ortonym]

Dishwater
or as dull as ditchwater
Probably both 😃
But which one do you know/use?
Any more ambiguous phrases out there?

It’s ditch. The water in a ditch is usually sluggish or stagnant, hence dull or cloudy in appearance, compared to a fast flowing clear stream.
I imagine modern city dwellers are less familiar with ditches, and have misheard it as dishwater, which makes sense to them as being dull grey or scummy.

Reminds me of my ex-wife !!!! .. xXx😎

Ditchwater.

Another vote for ditch. Suspect it only became 'dish' due to lazy enunciation or mishearing.

In that context dishwater is probably a better fit, on the NW we said ditchwater but would say something was as weak as dishwater (if we were being polite).

Ditchwater here too but it's an incorrect statement. Ditchwater is very interesting to anyone with an interest in wildlife, dishwater on the other hand is incredibly dull in comparison

Each to his own!