"the ground was boggy under foot"
"a marshy coastline"
"miry roads"
"wet mucky lowland"
"muddy barnyard"
"quaggy terrain"
"the sloughy edge of the pond"
"swampy bayous"

"muddy boots"
"a mucky stable"

"dirty"
"a dirty (or dingy) white"
"the muddied grey of the sea"
"muddy colors"
"dirty-green walls"
"dirty-blonde hair"

"a cloudy liquid"
"muddy coffee"
"murky waters"

"These data would have muddied the prediction"

"muddy the water"