The only problem with the expression, associated with the wisdom of entrepreneurs from northern mill towns, is that the only place you'll find real muck is in the countryside, usually on the underside of your shoe, as Mr and Mrs Ferret were reminded at the weekend.
And indeed, it now seems that money-making ideas are more likely to grow in the fertile soil of the countryside than in our towns. Research has found that most of the locations planned by new businesses across Britain are nowhere near the major cities.
The story was picked up by the national press and serves as a reminder to politicians of the England that exists beyond suburbia.
So who's behind this study? Good old further education, of course, the work having been done by Morel Research - part of Cornwall College.
The research found that young go-getters find the countryside more inspiring - even if they can't meet their clients in Starbucks.