Seems to me we have had this discussion before, but I will chime in again. I like and agree with most of Lonesome Gambler's thinking on the subject.
For the most part, I think red chip player should play rated. Their EV is so small that almost any extra EV in the form of free play and MP coupons can be a big boost their earnings as well as some comped meals and free rooms dramatically cutting expenses. Most casino's are fairly tolerant at the red chip level, unless you are overdoing it and making a nuisance of yourself like spreading $5-$200 or camping out at the table for hours on end or playing every single day.
When you move up to green to black play, like LG said, they begin take more of an interest. It is at this point that you need to weigh what your needs are and the pro's and con's of playing rated and value of the benefits to you. If you are anything more than an occasion, recreational player, longevity is an issue that must be considered in that equation.
For myself, my needs are little. I don't need any free rooms. I like to eat one pretty inexpensive meal on the casinos every day and that can be achieved by playing rated a very small fraction of the time which helps preserve my longevity. There are members on here that speak about receiving hundreds and thousands of dollars of free play and match play monthly. I am not at that level and my style of play (short sessions) is not conducive to that. I receive a few MP's, but mostly some free play. Nothing great in value, and if I weigh that against the risk, I can do without it.
There are those that say that playing unrated draws more attention than playing rated. That just has not been my experience. I am rarely even asked if I have a card. Again, maybe it is because of my style of play. I buy in for a small amount that immediately indicates that my stay may be very limited. I think many pit people look at that and say “I won't bother”. I suppose it might be different if I sat down and bought in for $1000 like I intended to stay for a while.
One last thing I want to touch on. There are some that like to play rated at certain properties and tone down their attack at those locations in order to receive comps and offers. In many of these cases I think the EV the player is giving up may be greater than the value of what they are receiving. Something along the lines of tone down your spread and your EV drops from $75/hr to $50/hour. You play for 6 hours and receive a comped room and meal. Cost in EV $150. You would have been far better off to have attacked the game full out and pay for your own room and meal. Especially these days when rooms are often going for next to nothing.