playing and spotting, two different questions
Snapper, you originally asked how to spot Mindplay, but that has nothing to do with your new question.
If you are a counter, Mindplay can help the house identify you as such and shorten your time on the tables.
If you are a BS player who bets big and has been given larger than deserved comps in the past, Mindplay may reduce the amount of comps you get.
If you are a player who never got the comps you think you should have but were afraid to ask, then Mindplay might increase these for you.
If you are any type of player and you play Mindplay in a place like the El Dorado in Reno, they just might shuffle away any deck where you have an advantage. Simply they will cheat you.
If you are playing somewhere else and you see them shuffle early sometimes but not others, you are probably being cheated.
Mindplay can be used to cheat players. Perhaps most casinos will not do this but if the ability is there, some casino will take advantage of it.
To answer you second question. No, it is not OK to play on a Mindplay table, unless you do not mind the possibility of the casino cheating you.