score:1
In my case, I found it easy to find space at the lot. I came in when the site said that the lot was completely full beyond capacity, but I was able to find a space just as someone was backing out.
A friend of mine showed up to the lot with the site showing that only 25% of the spaces were occupied, but with a clear signboard indicating that the lot was full. However, he looked past the sign and saw an empty space. The automatic gate let him through, and he occupied that space.
In both cases, the site was fairly out of date. I'm not sure how heavily the site is cached, but you can't rely on it for up-to-date statistics.
My suggestion is that if you plan to park at LAX, make a reservation at a far-off private lot that does not require advance prepayment, and arrive very early to the airport. Take a chance at Lot C and see if you can find an empty space. If not, just go drive off to the private lot you reserved. You will probably be charged $4 for the first hour in Lot C, but this is way cheaper than arriving a little later and finding that Lot C is full, then being forced to park at a nearby private lot with much higher rates.
Note that if you're planning to travel during a holiday, when there is a higher-than-usual level of passenger traffic at the airport, it's probably best to simply make a reservation and park at a private lot instead of spending $4 at Lot C before heading to your reserved private lot.