If your gut tells you the coupon is too good to be true, go with it, chances are you are right!
Also, you DO NOT want to get caught with a fraudulent coupon... (different from misusing coupons which is a very serious federal offense) it looks really bad on you! Obviously the store wont be reimbursed and suddenly they watch you like a hawk every time you come in the store and check out b/c "there is that girl/guy who used a fraudulent coupon last time!"
Tiffany at MyLitter just posted THIS post about these new coupons that have been spotted!
You can read more about Fraud 101
If you ever have any questions about coupons please go to the CIC (coupon information center) and look at the fraudulent coupon list and see if they are on there.