Yes, "all over the shop" is an adverbial expression meaning someone/something was haphazard, lacking in control, or behaving unusually.
"Messi [a footballer] was all over the shop"
might be said if he was regularly out of position in match, or performed uncharacteristically unskillfully. The verb is implied here.
If you say "mud was all over the shop" then the only interpretation I know is that a literal shop has mud over [the inside of] it. That's not idiomatic; it's just plain language.
It could work if you were talking about mud doing something unexpected; maybe a misbehaving oil well.
What's your interpretation of the full expression "there's mud all over the shop"?
