I do this now today too, but not even for potentially malicious software. Some projects that are not inherently malicious are just written poorly or stupidly by design. Just the other day I ran a program that, before I even requested it to do anything, appended 3 lines to my ~/.bashrc. I didn't even notice until days later. I can't fathom why any developer thinks this is a good idea, and is exactly the kind of thing that makes me sandbox every foreign piece of code I run now.