If I could track clickthroughs like you can with Bit.ly (you could always just sketchify a Bit.ly link) then you could do some security testing to see who will click on anything.
That said, the reason we've come to tolerate shorteners is that there's an implicit network of trust in the way they're used on Twitter. We trust that someone we follow isn't going to put a goatse behind that bit.ly because we know enough about them to believe they wouldn't (or at least we don't think they'd risk a massive loss of followers for it).
So by the same reasoning, if you send a ShadyURL to a co-worker, if they know you, they probably trust you won't be sending them anything malicious. Though I suppose the smart thing for a recipient to do would be to double-check with you that you sent the right link.
Now that is scary.
My happiness is confused. =) This is the best and worst thing I've seen all day.
go on click on it I dare you!!