I always thought casino games are reasonably close to fair. However upon teaching many math courses I learned that there are biases that are hidden. Lets focus on craps: 

On cheaper die they drill holes out of the dice. This makes the 6 side lighter than the 1 side. Due to gravity, the 1 side will land face down more often, making 6 more frequent. 

Similarly if the decals are painted on the dice, then more decals will add more weight. Making 6 heavier, meaning 1 will show up more often.

The dice are not fair look up the latest on dice bias.