Glad you had an enjoyable time snorkeling. When we were in Acapulco during our cruise on the Bliss, I had similar reservations about Acapulco. However we found Acapulco to be very enjoyable. We walked around the fort across the street from the pier, then headed down the road that parallel the beach about 3/4 mile. We found a decent beach spot with an umbrella, table and chairs for about $7 and plenty of locals and families . Very few vendors, but amazing tacos and mangos. It turned out to be a very relaxing day. Walked back to the ship and stopped by a flea market. There was a police and military presence throughout the area.
Everybody needs to judge for themselves and are responsible for their own safety.