Some of the posters above seem to be confusing two different types of line twist.
One is caused by some part of the end rig spinning on the retrieve. That could be the bait, offset shot, or whatever. (Worst culprits are blade spinners and devon minnows.) This type of twist is worst at the business end of the line but can often be alleviated by swivels and anti-kink vanes and suchlike. Too fast a retrieve is going to make this worse. I used to have a Mitchell 498 that could pigtail 15lb Maxima, just because the retrieve was so fast.
The other type of twist is that caused by the way a fixed spool reel works, and occurs more or less equally along the whole length of the line in use, although it will tend to concentrate in the area of the line most used, or most likely to be off the reel when the two main causes happen. These two causes are the drag slipping and/or the use of free spool systems. That is because when either of those things happen, line is comming off the reel as if off a revolving spool reel (think centrepin or multiplier) but being wound on again in fixed spool style. As Sean Meeghan said above, in normal use a fixed spool puts a twist in on the cast and takes it out again on the retrieve. (Although that depends on whether you wind the line on in the first place by letting the spool revolve or having the line come off the side. (And it's worse still if you pick the wrong side!)) So what happens when the clutch slips or the free spool system operates is that little or no twist is generated as the line comes off the reel, but twist is put in when you wind that line back in.
I would expect that the main reason some people experience very little twist is that they hardly ever have the clutch give line, probably because they backwind more than use the drag.
Oh, and as for sidecasters - they generate colossal amounts of line twist, for the reason I outline above, but in reverse - ie the line comes off fixed spool style, but is wound on revolving drum style. The only time you might get away without line twist being too major an issue with a sidecaster is for rolling meat - if the meat rolling on the bottom untwists the line, but the river would have to be flowing the right way!