"Even if digital signing were to be perfected you will still have to trust that the file is safe..." -- Unless!!... You've got some experience in reverse engineering (for information retrieval only) about how the file operates on your filesystem. If you notice some odd instructions; writing to another process memory, any AV references, any hooks on system information and queries, when the file is maybe just something like Photoshop or some Image viewer app you downloaded off the net. Then you've got some serious issues, and the file probably shouldn't be trusted, regardless of what the Digital Signature says.
"For example it is not uncommon for companies to release software that is not truly safe..." -- Nope, and you'll get that a lot with lots of the smaller companies. Larger companies like Apple, Adobe, Microsoft, etc... Will usually sign their stuff though.
"My favorite is when the user themselves are the issues... For example soldiers updating there facebook statuses with global positioning while under cover :banghead:" -- Haha, yes :) I read an article about that as well here posted by JMH. Just goes to show you that people do develop strategies, for the socially unaware people using a computer, or even to do with things that 'trick' your system itself, if they can't trick YOU. You can have Antiviruses, but you still have to keep your brain in high alert regardless. That's my rule with computer security.
It should be more widely known, but I know lots of even my family members that think an Antivirus is the best thing ever, and depending on whether it's even free or paid, determines how good it'll do for protecting your system. Otherwise if it can't protect it for you, then nothing can. Which is all a bunch of false information I believe (for the most part).
