A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

Note: 
a) The expression is not antonymous in meaning to the
phrase pretty penny, a— a fairly large amount of money: You
can expect these tape decks to cost a pretty penny, although
no price has been set as of yet.
b) The expression is not antonymous in meaning to the phrase
honest penny, an
— money gained or earned by fair means: I,
then a mere stripling, was trying to make an honest penny by
selling homemade candy.
bad money drives out good • bad penny always
turns up, a
bad money drives out good —(saying ) worthless people or
things supplant more valuable: The drain of human resources
is one example where “bad money drives out good.”
Note: 
The expression does not correlate in meaning with the
phrase throw good money after bad— waste more money or
supplies in hopes of recouping previous losses: Creating another
failing system to replace the current one is throwing good
money after bad.
bad penny always turns up, a —(saying ) a worthless person
always returns: “What if I never see him again?” “Don’t worry.
A bad penny always turns up.”
bad mouth • foul mouth
bad mouth —
1
. a curse or spell: I have known of people that
have had the record of saying that they could put a bad mouth
on you. 2. malicious gossip: Companies don’t want people
telling their friends about shoddy products. Word of bad-
mouth can kill them. 3. a person who speaks ill of people:
The world is filled with bad-mouths. We need more caring
people.
foul mouth —(also: dirty mouth) a person who uses obscene
or abusive language habitually: Terry is turning into a real
foul mouth.
bad news • what’s the bad news
bad news —(U.S. coll.) said of things, people, or places that
are unpleasant or undesirable: Milly these days was plain bad
news. Her fascination had evaporated.
what’s the bad news —(U.S. joc.) what do I owe: After the
clerk had run up all of the clothing Meg had selected, her
mother nervously asked what the bad news was.