Don't know about smell bad - I've always stayed a respectful difference away (as does anyone who knows about koalas). They may 'look cute' like a fluffy bear, but they have seriously BIG claws which can inflict some damage on a human - designed to grip hard tree bark. While the Oprah-Over-the Top-Show was on here, a pic of her appeared on the front page with a koala clutched to her chest. Us women cringed at how close those big claws were to a sensitve portion of our female anatomy.
As for roos - yup. Can be very dangerous. Nothing to compare with your big bears of course, but they can and have dismembered an unwary dog with a well aimed swipe. Again, big claws. I prefer to observe all from a distance. I'll save cuddling for cuddle-worthy pets.