What you are describing is illegal in all U.S. jurisdictions with casino gaming. Video poker is the only slot type game that a knowledgeable person can determine the payback by knowing the pay table.

A slot route company called American Gaming reprogrammed machines so a Royal Flush could not be hit with a max bet. They were shut down by the Nevada Gaming Control Board. The programmer of the gaff was murdered, this was attributed to the owners of the company attempting to cover up their illegal actions.