I just wrote this sentence (shortened, so not literally) on a different StackExchange site:
Of course it's very easy to purge the exact packages which have been installed by that if you still have the output.
Should the be a comma after "Of course"? Had I written something like "Evidently, it's very easy to ...", I'd feel like there should be a comma in there. But the above sentence doesn't feel right with a comma nor does it feel right without one.