Betting for comps: Black and red, odd and even, pass and dont pass

Any of you ever do bets only for comps such as playing simultaneously: black and red, or odd and even at roulette, or pass and don't pass at craps? Now that there are many electronic "table games" you can do this. I don't know of any restrictions on it at the electronic table games. If there are cash back or free play bonuses, it might make even more sense? Any info on this? If you did it, did it work or backfire?

I did this a couple of years ago, as did others, at Wynn to quickly rack up some points for free buffets. It worked -- I used the electronic roulette and lost about between $5 and $10 per buffet, which was going for about $35 at the time. I don't know if you can still do this.