I have limited experience in this area but these are my observations over several years
It seems to me that most of the Philipino gals work as SP's at incall apartment locations rather than at Spas. There seems to usually be 10+ that advertise regularily on LL. As a rule they are reasonably attractive and usually are in their 30's or 40's. Also they are generally very reasonably priced. Reviews usually are at least decent with little or no evidence of bad service /no service/pimps etc.
The only real reservation that I have with them is that they seem to work long hours, sometimes advertising several times a day and in my opinion they are often very high volume as indicated by the 2 that I have seen over the last few years.