If you are observant enough, you can somehow cheat. This is not 100% sure but it helps a lot on deciding a bet.
This is not about cheating but this is what the actual skill which is doing the real magic in gambling.
I agree that only skill-based games can provide regular profits to professionals. One can of course exploit some troubles with games on certain websites or in physical world, but that is not fair and will probably eventually be revealed anyway. That colour game sounds like a fame of chance in perfect conditions. It might be that in real life the angles are not perfect and the ball falls on some colours more often than on others, but I wouldn't count on that. After all, it could be a coincidence, or maybe even that same place will use another desk (or whatever they use), but you won't notice and will lose big time.
Yes the playing method will be the answer to get the profits so make the quick sense that you are doing something with knowledge and experience it will be successful in any kind of situation.