The Trouble with Ticks

The Men In Black have a serious problem. They have captured three of the pod-people of the  Hodgepodge system sneaking out of Manhattan. These creatures look identical; but looks can be deceiving. The pod-people are evenly divided between the Heretics who live on the largest planet and the Lunatics who live on that planet's moon. Now, the Lunatics believe that the only way to get ahead in life is to lie. Their religion states that the only way to get to heaven is to lie through your teeth. The  Heretics, originally a splinter group, broke away from the Lunatics and settled on the harsh main planet. They  believe that honesty is the best policy and, of course,  are honest as the day is long. Their "day" is almost twice the longest Earth day.

While the pod-people are identical in appearance they can be distinguished by smell. Three prisoners have been unofficially named: Rose Petal, Skunk, and Munster. Unfortunately, smell can not distinguish religious beliefs or ideologies. All three are successful intergalactic industrial spies. Each brokers for at least one and often several interstellar firms.

When questioned why they were leaving New York:
Rose Petal said: "This planet is about to be invaded by Havoc Robots! They have the tendency to destroy everything organic in sight. You'd best buy defensive armaments  from my company, Brodigan INC."
Munster said: "Someone, I can't say exactly who, although I have my suspicions,  has nudged one of the comets into a collision course with Earth. Of course, I just happen to have some equipment that is designed to prevent such a catastrophe. I'm sure we can agree on a fair price.
Skunk said: "Unkaquakkoopie poopiedoo." (Apparently, although he doesn't speak a known Earth language, he seems to understand spoken English or else he has a working translating device. Unfortunately the men in black don't have any way to comprehend what Skunk is saying)

The Men In Black (just to be absolutely certain) use  English, as well as images and hand gestures to ask the question:
"Are you a Lunatic?" to Skunk.
Skunk replies: "Stwapolus furù^ner!"
They then turn to Rose Petal and Munster for some help:
Rose Petal : "He says he's not a Lunatic."
Munster : "He says he's  a Lunatic."

Who is lying and what should the Men In Black do?