I competed in IASCA in 2000. I finished in 5th place in the World Championships in Oklahoma City.
They check everything ninspeed mentioned, plus...
When you get to that level of competition, everything is in the details. Everybody in the finals has a great system. You absolutely need a photo book of your install. You need pictures of everything the judge can't see. Are the wires properly soldered? Is there any gaps between parts of the system, or between the system and the rest of the trunk? Are screws visible or not? (not visible is better, cleaner look). At the World Finals, they were checking if the crosses in the centre of the screws were aligned across all screws. Is there a theme carried throughout the vehicle (important)? Can you get to your fuses and replace any of them under 5 minutes? You get bonus points for originality, unique setups never seen before. I got bonus points for my 2 EQTs installed in the rear side windows. Cleanliness. Attention to details. the more custom stuff, the better. I had all my amps and all audio control hardware (EQTs, Epicenter, 4xs) chromed and resilkscreened in blue to match the theme of my car, and to make sure it would be unique.
MH
On a clear disk, you can seek forever...