This is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles.
If a word conforms to a special rule, I call it a Rotten Word™.
Use the following examples below to find the rule.
And, if you want to analyze, here is a CSV version:
Rotten Words™,Not Rotten Words™ ANT,BEETLE BARF,VOMIT CLERK,TELLER EBBS,FLOWS ENVY,JEALOUSY FLAP,FLUTTER GNAT,FLY GREEN,BLUE NOWHERE,SOMEWHERE NUN,PRIEST PURELY,MIXED REEF,OCEAN ROOF,CEILING VEX,TROUBLE