Bali is on my list of safest places to travel, but I still watch out for my valuables. 99.9% of the people may be honest, but there is always that .1%.
I've traveled to Bali since 1990, stay there frequently and have only had a problem one time. It was at a largish hotel in Kuta. Someone came into the room in the middle of the night while we were sleeping (apparently they had a key, we suspect an employee) and took a huge wad of travelers checks. Mosquito's got into the room when the door was open and they woke me up. We saw the door open and the silhouette of someone leaving. We immediately reported the theft to the office and then went back to the room and to bed.
The next morning I opened the door to step outside and the travelers checks were there, neatly folded in a paper, about 2 inches from the door. Would have been a great ad for American Express travelers checks!
Over the years (many, don't ask) traveling all over the world on business and on holiday, I've had a few items taken from hotel rooms while I was away, or from a bag sitting beside me. The latest was my favorite ring - the opal cracked so I put it in with my junk jewelry to take home. When I went to get it out after the next day's tour, it was gone. That was in Scotland in a very lovely boutique hotel.
My opinion: When traveling, you should always lock up your valuables. Money, passport, etc.
On our last dive trip, one of the guests stole things (verified) from the Indonesian divemaster, the ship and the cruise director!
I have never felt uncomfortable or threatened anywhere in Bali. Hmmm.. except by those macaques that hang around the Monkey Forest entrance in Ubud.. watch out if you walk by with food.

