Yeh, it's very annoying for sure. There are those that may not be aware that they might infect someone by a trojan or some other virus by sharing an executable on their computer. But as you point out there are others that explicitly implement nefarious code in their "script" to do all kinds of bad things.
That's kinda why I want to look into updating ScriptUO to allow for people to load a .cs file into the editor, and have it compile and run. At least there you can see if there is any evil code embedded.
With .net, one could use .net reflector to look at the assembly, but it's pretty easy to hide, compress or obfuscate the code to get around that.
From my viewpoint, I'd be pissed if someone got a virus by running items acquired at this site.