When comparing ClamXav vs AppTrap, the Slant community recommends AppTrap for most people. In the question“What are the best Mac OSX apps for someone that's new to Apple?” AppTrap is ranked 18th while ClamXav is ranked 28th. The most important reason people chose AppTrap is:
AppTrap installs a daemon that runs in the background monitoring the trash, when you drag an app to the trash it will search for associated .plist files that have been left behind and ask to move them to the trash. In other words, AppTrap launches and does the work for you automatically. All you have to do is uninstall apps the old fashioned mac way by dragging apps to the trash.
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Pros
Pro Monitor directories easily
The Sentry Feature monitors specific directories 24/7 as well as removable media which includes USB & external drives, all those .dmg files you open when installing apps etc. I add all directories that files are downloaded as a "screening" process.
Pro Lean
Not overly invasive or processor hungry as other antivirus programs
Pro Prefpane style app
AppTrap installs a daemon that runs in the background monitoring the trash, when you drag an app to the trash it will search for associated .plist files that have been left behind and ask to move them to the trash. In other words, AppTrap launches and does the work for you automatically. All you have to do is uninstall apps the old fashioned mac way by dragging apps to the trash.
Cons
Con Does not monitor or protect ram memory
Con Not Supported in Big Sur
Con Gets some things, not everything
This is thorough enough in cleaning up most of the cruft that gets left behind by applications, but might not get everything for the more invasive applications, especially if some of the files have privileged permissions.
Con Requires using Finder
Does not work if you trash app using alternate file browser like Path Finder.