morphiak yes, you may be overthinking things a bit but I'd say we're all guilty of it at some point.
While there is nothing wrong with creating profiles to test out various apps, it really isn't required unless you're trying to isolate those apps from seeing a list of your primary apps or potentially sharing your personal information with them through use.
As far as I know, there is no way to "pollute" a profile by repeatedly installing and uninstalling apps, as all apps are sandboxed anyway. My understanding of the Android security model is that apps are essentially compartmentalized, like a virtual machine. When you uninstall an app, you're removing it in its entirety, including any data and metadata that was created within the system folders. There won't be anything left of it to "pollute" your profile unless you actually save or export data from the app to another location yourself.
As for Rethink, I've never heard of it so I can't really comment.