I think if you want to do this, you need to

1. use a casino that is very trusted and doesn't use compliance as blind excuse to freeze coins
2. use a trusted mixer that has good aml score and clean coins

If you use shady casinos they will use any excuse to steal your coins, and mixers can be safe to clean coins but many just use customers coins as the sourced coins so you could be getting dirty bitcoins that are worse than your original ones.