I too have experienced "shark attract" dives as well as seen sharks just cruising by in the daytime or hunting by night. I much prefer to see them without any manipulation. It's the same for the famous manta night dive on the big island of Hawaii. What a disappointment the experience of sitting around on the sand holding huge lights up to attract the plankton so that the mantas will come when I compare it to waiting on the ridge at Koh Bon island here in Thailand and seeing them come in to feed without any particular manipulation of the environment.