They are truly supposed to be random. But it is said that some casinos program the machines with less probability of jackpots. So what people like you and me do is play at a casino which guarantees 100% fair game play. Most of the online casinos guarantee that.
Shorts, T-shirts, short-sleeve shirts, and sweatshirts are not allowed, let alone flip-flops, so if you've spent the day exploring Monte Carlo, be sure to change before. Pro Tip: Some rooms require men to wear a jacket.
Casinos tend to be more casual during the day than at night. Males should stick to collared or button-down shirts and women should wear blouses and other formal clothes. After sundown, it is best to avoid wearing shorts and t-shirts. The higher the status of the casino, the more formal you should dress.