Even if that directory was deleted, the exact version of every Creative Suite app is included in the info.plist file that is inside each application package — that’s a far more logical place for the updater to look to find what version the current install is.

After all, the mere presence of the .AdobePatchFiles directory doesn’t perfectly indicate if the patch was installed, I don’t believe … a crash during the install would leave the entire directory there, with only some files applied.

That all said, if you ran into some future problems and told Adobe tech support that you’d deleted said files, I’m sure that they would say “We don’t know if that may have caused your problem, and we don’t advocate doing that, so you’re out of luck.”

(Adobe have popped into Dirty Words before to tell me when I was full of shit — politely and professionally — and they’ve yet to do so for this post …)

However, I think it’s worth a warning that one should have their original CS4 disks, and probably a backup before attempting anything like this: patch files, as one might expect, keep track of the differences between different versions of your CS apps. Deleting these files could cause future CS app updates to fail.