One of the first things we were told in Pueto Angel is that there are many drug dealers. Our waiter told us that they can be found along the road from P. Angel to Zipolite and we should avoid that road in late hours. But I didn't feel threatened in any way. My only experiece with drugs was, when I rented a room, I was offered to buy marihuana (BTW, I didn't).
When going swimming you must be very careful. On the Pacific coast the waves can be very high and danegrous. Plus there is a quite strong current. That makes swimming not only dangerous but also not very enjoyable.
Well, the situation in Puerto Angel is better than in some other beaches nearby, because it's situated in a bay.