I'd add that you don't even need to have the machine actually be compromised. If you think it might be compromised, if you have reason to believe that perhaps

I'd add that you don't even need to have the machine actually be compromised. If you think it might be compromised, if you have reason to believe that perhaps something bad happened, you probably should re-image it. There may be smoke without a fire, but it's not worth the risk, is it?