Actually, you can be tracked if you use movement tools to bypass your normal movement speed with the equipment and JAs you have active. One of the most telltale signs of a pos.exe hack, for instance, is the uncommon inability to zone. You actually fly past the zoneline, and hit the map render border. Now, this can happen to any normal player, but the odds of it happening due to lag is somewhere around .0001%, but the occurence with pos.exe happens much more often. I've seen it a number of times just walking around.

But, no, that's not 'file checking programs', TractorCow. That's the server reporting abnormal or glitched movement to a troubleshooting server, or as SE could easily do, directing those reports to their third-party tool investigation teams. Actually, anytime your character or any character skips too many x,y cooridnates in a row on a path, the server should notify just to make sure the problem is reported, isolated and resolved.

It's fairly obvious they don't do filechecks, though. You can intiate a filecheck through POL, but filechecks tend to be pretty obvious, from prior experience. If you've ever had a small framerate drop while playing a Punkbuster-enabled FPS, or have had to wait 60 seconds or more to enter a server, you'll see that the log-in delays and check spikes are fairly detectable.

Lot of those things Punkbuster does actually doesn't check your files. Your avatar sends data to the client-side program constantly, checking for abnormal movements, actions and data that shouldn't be there in normal play. Since it's a passive receiver, and client-side, it creates little to no noticeable effect. You will get a lag spike when it decides to report up to the server if you get busted, though. Notice with Punkbuster, is that the game bogs down, freezes up, then boots you out if you've ever had outdated definitions, or just met some requirement for Punkbuster to give you the boot from that server.

Well, I think I went off on some tangents in this post, but yeah...active, passive, normal troubleshooting procedures. Possible and less then achievable methods for detecting hacks. SE's done well in knocking out the RMT they have done, and the hackers, but there is still room for improvements. I'm all for Punkbuster, obviously, but that's because PB is pretty much 99.9% effecient when it's caught up to the game, and it works instantly.

There's nothing illegal about them checking your .dat files.

They would just be running a pre-start up check on their game files to ensure nothing is corrupted, using a simple CRC check, and then download patches to fix/repair any corrupted files they found.

I'm suprised they don't do this already. (not all the time, but occasionally).