You can say something stinks in your Amazon or Yelp review -- but you can't lie. A Florida man may be about to learn that lesson the hard way.

The man is being sued for claiming the product he reviewed on was identical to a cheaper one from another company and he suggested positive reviews of it were fake. Houston Internet law attorney Travis Crabtree says that's more than just an opinion.

"If you are gonna say something that is patently not true -- I'm not talking about opinion but a false statement of fact about a product or a service -- then yes, you need to worry regardless of where you post this."

Crabtree says Amazon and Yelp reviews carry a lot of weight with consumers and companies are trying to crack down on reviews they consider defamatory.

"It's perfectly legitimate for companies to pursue these claims if they know this is either their competition, it's a fake review or someone is out there just spreading outright lies about their products and services." 

Crabtree says reviews on Amazon and Yelp are influential with consumers.