As Common as Muck

How do I manage to spend hours upon hours on the Internet? Curiosity, mainly.

I start with trying to share information I have with you, then stop to check that it's up to date, then find something else interesting, and so on and so forth.

I was looking up some information about a food called 'dory'. Turns out it's actually, unbelieveably, A Fish Called John Dory (which was very nearly the title of this post). Then I went to see when this fish is available and it turns out pretty much all year round. This made me wonder why we don't have a saying, "Common as John Dory" and in trying to figure out what people say "It's as common as ... " (I need some help here, I've lost my American...)

Turns out what they say over here is "Common as Muck" (and there is a movie with that title about bin men).

Sounds grubby to me.