What do the following words have in common?

COW
BAD
WET
SHOW
DYING

HINT:
The same three-letter word can be inserted into each clue to make a new word.

Answers:

Inserting the word ALL into each clue creates new words:

CALLOW
BALLAD
WALLET
SHALLOW
DALLYING 

Credit: NY Times Crossword
Matt Skoczen
ALL IN  (adapted)