| be foul | 3.75 | It was foul. | ||
| fall foul | 3.23 | He had fallen foul of the FBI. | ||
| go foul | 1.58 | The first one went foul. | ||
| smell foul | 0.39 | The liquid smells foul. | ||
| turn foul | 0.39 | By Sunday evening, the weather is supposed to turn foul again. | ||
| become foul | 0.33 | When did writing about God on the sports pages become foul? |