most dui arrests (at least mine) are not your drunks. they are your weekend warriors or seldom drinkers. all over road, cause absurd wrecks, just painfully drunk, and it is obvious. whereas your daily drinkers, they are not going to drive like that. they're usually not exhibiting bad driving until north of the .25% range. whereas your less "experienced" per se, are driving like CRAP as low as .12%.
I have had best luck with turn signals (not not using them as you'd expect... but leaving the damn thing on for a mile) and needless lane changes. left to right to left. inconsistent speed is another great indicator. and yes
@larry_minn is correct nothing screams "this person is hiding something" more than hands at 10 + 2, the world's most gentle acceleration to precisely the posted speed limit, blinker etiquette that would make a trooper get an erection, gently applying brakes, etc. the fact is, no one really drives like that. when they have nothing to hide, at least.