Well, for me, if there is any mud, it depends on where it's coming from. I'm no expert, but I usually try to fix it individually instead of applying an EQ cut across the whole mix. I'd go into the project, play it, select the bass track, and look at how your bass is EQ'd. Setup a moderately narrow Q setting and start pulling down in that general 200-400 area - while the whole mix is playing - until the bass tightens up. Pay close attention to the kick/bass relationship. They should both support the bottom end without mushing together. Just my 2 cents.