BFG10K and RoboTech,
in the case of Quake3, yes, these are things that are not likely to pop-up (all the Quake series didn't really suffer from this much, although a few custom Quake2 maps did have the same problem).
But in other games like Half-Life, this problem is more apparent - trust me, you dont have to look for it. It doesn't effect game play, but you can 'see it' - if you know what I mean. I have also seen this a couple of times in UT.