They didn't give any examples
There's a lot of "Will Someone Think Of The Children!" in this -- the researchers seem to have set up a bunch of useless sample skills (applications) in such a way that they'd pass certification so that they can get a tabloid type headline out of it rather than trying to figure out what does and doesn't work with the skills filter. For the skill itself to be useful it has to be identified and installed which might pose a problem since it will be difficult to get people to willingly install nonsense.
Although the Echo is now several years old as a concept I still think of it as a work in process. It relies on a lot of goodwill by both developers and users to be successful and its not a platform I'd trust with sensitive data just yet. ("Bit it can listen in"......"sure, there's the haystack, let's find the needle") The concept shows a lot of promise, though. Deliverately vandalizing it to prove that you can 'just because' has about as much relevance as spray painting obscenities on a wall.