Pad misses are part of the game.  Especially in tournaments. 

...but a bad one that ought to be minimized by whomever operates the machine. That's who this is for.

Stale2000 - yeah, uh, no. Misses are part of the game if you suck at hitting the arrows. Pad misses don't happen on a "healthy" pad.

I will agree that the pads are often put under too much scrutiny at tournaments - if players are getting similar amounts of pad misses on both sides, it's not hard to factor for that and do some kind of arbitration that doesn't require hours of bitching and repairs. But you can't say that the game being broken is just part of the game.

@Stale2000: Pad misses happen, but on a properly-maintained machine "happen" means once every 5 sets or so from what I've seen (even less frequently for me since I'm bigger than most players and the "every-few-sets" transient miss is from centering a step on a loose or dirty sensor, not a damaged/dead one).  Misses will happen even less frequently on a well-maintained machine or one in a location that doesn't take much abuse (I've seen machines where stuck sensors were caused by the presence of spilled drinks that seeped under the arrow and made the moving parts literally stick to each other) - normal wear and tear is pretty easy to undo with some simple cleaning and tweaking, but many arcades subscribe to the idea that you can let it go until parts are absolutely necessary and the players won't notice (which ironically means they spend more fixing the machine and it's in worse condition on average).

Arcades wanting to host a serious tournament should be willing to give the machine a cleaning beforehand and adjust the tension of the sensor brackets, which will fix everything but a truly damaged sensor.  Damaged sensors can be rotated to the outermost positions rather than replaced without players being able to tell unless the sensor is truly dead (even then, it won't cause too much of an issue).  If a machine gets enough play that sensors need to be replaced regularly, the machine probably makes enough money that the replacements parts aren't going to impact profits too much.

All in all, pad misses will happen, but a properly maintained machine will have them so infrequently as to not impact tournament results past the point that simple score recalculation can determine a definite winner following 95% of pad misses.  I've seen a machine in poor condition (IZ's ITG machine at Sakuracon '06, which had damaged or dead sensors in 20 of the 32 slots - we moved 6 per side into the most important positions and hoped for the best) let a player pull off a 4000 combo over multiple songs, so you really can't say that a machine with decent parts and regular maintenance (even 20 minutes of cleaning once a month) absolutely has to give you misses with noticeable frequency and that tournament players should just suck it up.

Honestly, the most important part of keeping these machines in order isn't even scheduling regular maintenance and replacing parts left and right; actually listening to the player's input and looking into potential issues they bring up lets you get away with very low investment (in terms of time and money) to keep a machine in top shape.  A detailed and exhaustive sensor check like ddrcoder's should not actually be necessary more than every once in a long while, because the parts were designed to take a pretty heavy beating.