http://blog.emsisoft.com/2015/01/27/top-10-ways-pups-sneak-onto-your-computer-and-how-to-avoid-them One reason why I DONT LIKE INSTALLERS! I try to find ZIPs or the EXE itself... Ya dont know what they might try!! (Especially with FREE stuff today!!)
from an admin perspective this could be handled a number of different ways, depending on how knowledgeable the users are. first, just limiting install rights would probably cut this down by 90%. the smarter users might learn to do local installs on their accounts but this can be easily handled with group policies, but just limiting admin rights would probably be enough in most situations.
install from source. compile and build yourself, you'll know what's in there because you can read all the code ... obviously it has to be open source, some random program that you can't look at the code im not sure I would trust.
a lot of malware can do a lot of damage when they fuck with the shared libraries and replace .DLLs in windows which can cause problems even after uninstalling. they never tell you what they're going to do either (like what they're depndencies are and shit like that).... any shared runtime libraries a simple free program needs should be either linked against common libraries or installed in the install path of the program (c:\program files\...). what a (nice) program should NOT do is replace common libraries with alternate versions or touch the configuration of other parts of the system. that's a bad design if that is required for the program to function and has a high chance of breaking something.
Yeah, since people can read all the languages that these apps come in, right? I bet you have all of them down by now...... OR Just have one comp for everyday stuff knowing that people and gov. see it and another one that is secure and only for looking at certain things and all the "stuff" you don't want other people seeing or knowing.