I know Mitchell talked about this, but let me expand on this a little. As I'm sure you know, just importing a macro can't cause any harm. It's only if the macro gets triggered that there might be an issue.
So before I import a macro from someone I'm not familiar with, I want to make sure that if there's any triggers I might not like - specifically, something that gets triggered more-or-less automatically, the triggers are disabled when I import them.
That's one of the reason's I wrote my Macro Import Manager. It forces me to examine the macro first, allowing me to disable any undesirable triggers before importing. The second reason is that I can change the Group so they go where I want them to go.
So my feeling is this: As long as I use MIM to do the importing, I don't worry too much about what macros I import. And believe me - I'm pretty careful with stuff other people wrote. 