Getting paid for testing products: Too good to be true?

I recently saw an ad on television about a website where they pay you to test products and take surveys. In fact, over the years I've seen multiple ads like this. Are all sites like these scams, or are some actually legitimate?

I ask because as a college student, earning some extra cash for doing next to nothing sounds great, but at the same time almost too good to be true. If there are some real--and safe--sites like these I'd like to hear about them.

Thank you!