I think it's part mental, part physical. Call me the odd man out. This response is based on play in bars.
If I don't want people to think I am a ringer. Here are some things I won't do as I think it's a complete act, not just your stroke that can give it away.
1: Will roll a bunch of cues off the wall to see which is straightest. Now you would think this would give you away, but it doesn't. A ringer will grab any cue off the wall and from hitting a couple balls, know if he needs to grab another cue.
2: Do not, do not, do not chalk the cue like I typically do. If you see some chalk a cue in a consistant manner going across the tip in a shaving motion, they probably have played a game or too. I will chalk my tip by twisting the chalk on the cue. I won't use the best piece of chalk either. I won't chalk after every shot either.
3: I will not check my stance, grip or arm motion.
4: I may not even take my coat off.
5: Now once I start shooting or warm up, I may hit balls firmly into the rails just to see if they are dead or not. Banks as another member suggested.
6: I may just hit hit balls around and pay attention to how they roll.
7: If I pocket balls, they are straight in shots, hit fairly quick with no preshot routine and hit them sorta hard like a typical bar banger would. Getting or showing no english ability.
8: When finally playing someone, talk outloud, drink between shots, make jokes, anything that is out of the norm of a great player. Then, if you get them enjoying the game even if they are losing "ohh so closely" you can put a couple 3-4-5 ball runs together and they won't be so mad. "Everyone gets lucky once in 5 games."
9: If they are being good sports about your game, compliment them back. Even if they suck and truly show it. Compliment them. It will make them enjoy the game more and keep putting quarters up. Nobody likes to give money away, but if they are having a good time playing a good game, they will stay interested.
10: Lastly, you should know even if you are playing sloppy pool, when it's time to tighten your game, slowly back off much of the above and zero in your focus.
Never done any of this, read it in a book.

ez