[bolgenmod]

I'm sure that obsessively neat stacking might be a tell, but in my (admittedly limited experience), most people are somewhat neat with their stacks.

The place where I've found this tell to be most true is for those people who don't stack their chips neatly. Both at the casino and at the home game, the absolute biggest maniacs I've ever seen made heaps, not stacks of chips. The guy at the casino was amazing: raised every hand, played every hand, lost most of them. When he had chips, they were just a pile mostly in front of him, different denoms mixed together.

In short, like many tells, I think this is most reliable at the extremes, not necessarily for the vast middle who arrange their chips fairly but not obsessively neatly.