If the OS is intact, the job of checking whether a user environment is compromised is easy and actually doable (as opposed to the case of trying to find malware on a compromised OS).

If, in addition, a user account has limited privileges (which it should of course), then even when compromised the chances of malware being able to do a lot are a lot less. For instance, turning off a webcam light being a root is probably easy, otherwise probably not. Setting up a server, listening for incoming connections and punching a hole in local firewall as root is available, but as a regular user is not.

Stop giving admin rights to your computer to random people (install software as an admin) and live much happier. As an additional benefit, there's never a situation 'I installed this and now computer is messed up, because Joe-the-dev ran "rm -f " with a wrong path as a parameter'.