Why do people laugh in commercials?

This Is a Really a good question. they just want to show like that they have used/subscribed/consumed that product & they are happy. They like to tell the people that if they use that product they will be happy & smiling always without Thinking of that part of Life.

commercials is a good way for us to know what we can benefit from a product. and in today's commerials on telly, most were done nicely and i can say, to get a viewer's attention, they make their script really funny. that's why most people laugh in commercials.

Yes i have observed this aspect in all the commercials people are happy and laugh a lot, have such a beautiful smile on their face. I think they smile to make the commercial more attractive for the target public. Usually for the commercials are cooptated great actors, fotomodels and other personalities to make it more attractive for the public. Good luck!