It is not all about liars and we can think it in the other way: it involves lots of others things:
1 train your observation;
2 collecting detailed information from other pp's words, facial expression, body language and also any sounds you heard;
3 analysing all of the information you have;
4 using some strategies to make your words;
5 testing how well you know your friends.
6 kidding each others and lots of fun!
so the important thing I think is to play with your friends! So you can enjoy the game.
I played once with 7 friends and felt it interesting. But maybe others didn't enjoy as I did