Casinos cannot legally withhold slot winnings unless there are valid reasons, such as suspicion of fraud, non-compliance with gaming regulations, or issues like outstanding debts or unpaid taxes. If a player wins, the casino is generally obligated to pay out, but they may conduct an investigation if they suspect cheating or other irregularities. In regulated jurisdictions, casinos are held to strict standards, and they must ensure fair and transparent payout practices. If a player believes their winnings are being unjustly withheld, they can usually appeal to regulatory authorities for a resolution.