Dumaguette is the ONLY way to Siquijor to my Knowledge
The beaches and diving seem to be the main draws for tourists. Some Filipinas will NOT want to accompany you if you tell them you are going there as it is considered "haunted" by witches or evil spirits AKA "Mumu".
I have the number, somewhere, of a taxi driver/bugaw who can obtain Uni girls. I was VERY unimpressed with the girls at Why Not. There were a few cute ones, but they are hired just to dance and look nice but do not "go out" (although surely if you put in the effort to charm one."
Dumaguete at night: is there any "there" there?
I found myself in Dumaguete the other day with a night to kill. The only place interesting I found was called Why Not, facing the water on Rizal Boulevard between Locsin and San Jose Streets. It is a restaurant/internet café/travel agent/FX dealer/pool hall/disco.
There were a number of Arab looking guys playing pool, all quite good. By 11pm lots of nice girls, but no one who looked like they were working. My guess is they were looking for fun and BF. I was not getting approached or even seeing the overt moves of working girls, but was getting lots of smiles like from what looked like GF material.
I then went on walk about. As I left there were several tricycles parked out front, one with two girls in it. The driver approached me and asked if I wanted company. So there were some girls working in Dumaguete. I did not ask the rate.
I did keep walking the nearby blocks but did not find any interesting bars. I walked the waterfront where there were a number of groups of girls, but did not get much interest. There was one bar with lots of locals inside, but it did not look particularly welcoming for a foreigner, so I kept walking.
So if you happen to be stuck her for a night, check out Why Not. Else go to bed early and move on in the morning.